Solid electrolytic capacitor and method for producing the same

ABSTRACT

A solid electrolytic capacitor includes a valve acting metal having microfine pores, a dielectric film formed on a surface of the valve acting metal, and a solid electrolyte layer provided on the dielectric film, in which at least a portion of the solid electrolyte layer is of a lamellar structure. In particular, a solid electrolytic capacitor includes an electrically conducting polymer having a specified condensed ring structure containing (1) a solid electrolyte layer containing a sulfoquinone anion having a sulfo anion group and a quinone structure and other anion, and (2) a solid electrolyte layer containing an anthracenesulfonate ion and other anion.

[0001] This application claims benefit of earlier applications based onU.S. Patent Application No. 60/106,967 (Filed: Nov. 4, 1998), U.S.Patent Application No. 60/106,968 (Filed: Nov. 4, 1998), and U.S. PatentApplication No. 60/106,969 (Filed: Nov. 4, 1998).

TECHNICAL FIELD

[0002] The present invention relates to a solid electrolytic capacitorutilizing a specified electrically conducting polymer as a solidelectrolyte. More specifically, the present invention relates to a solidelectrolytic capacitor capable of realizing down-sizing, high capacityand low impedance of the electrolytic capacitor and having goodmoisture-resistant load characteristic and excellent heat resistance aswell as excellent thermal stress relaxation characteristic and to amethod for the production of the same.

BACKGROUND ART

[0003] A solid electrolytic capacitor is a device which comprises ametal foil subjected to etching treatment and having a large specificsurface area (anode substrate) on which is formed an oxide dielectriclayer and a solid semiconductor layer (hereinafter simply referred to asa solid electrolyte) as an opposing electrode outside the oxidedielectric layer and preferably further an electric conductor layer suchas an electrically conducting paste. The device has an cathode leadterminal connected to the metal foil and an anode terminal connected tothe electric conductor layer and as a whole is completely sealed by anepoxy resin or the like and is put into use as a capacitor part inelectric products over a wide range.

[0004] As the method for forming a solid electrolyte layer, there haveconventionally been known a method of fusing a solid electrolyte onto adielectric layer which has been formed on a metal surface and has aporous or fine void structure to form a solid electrolyte layer on thedielectric layer and a method by producing a solid electrolyte on adielectric layer.

[0005] According to recent digitalization of electronic equipment, anincrease in the operation speed of personal computers, a compactcapacitor having a high capacity and a low impedance in high-frequencyregions is being demanded. Hitherto, as a capacitor having a highcapacity, there have been known electrolytic capacitors such as analuminum electrolytic capacitor and a tantalum electrolytic capacitor.However, an aluminum electrolytic capacitor has problems that it has ahigh impedance in high frequency regions because it uses an ionconducting liquid electrolyte and also has a poor temperaturecharacteristic. A tantalum capacitor, which uses manganese oxide as theelectrolyte, has a problem that it has a high impedance in highfrequency regions since the manganese oxide has a relatively highspecific resistance.

[0006] To cope with the problems, it has been heretofore proposed to usean electrically conducting polymer having an electron conductivity asthe solid electrolyte. For example, there has been known use of polymerssuch as an intrinsic electrically conducting polymer having an electricconductivity of 10⁻³ to 10³ S/cm [JP-A-1-169914 (the term “JP-A” as usedherein means laid-open publication of unexamined Japanese patentapplication) (U.S. Pat. No. 4,803,596)], polyaniline (JP-A-61-239617),polypyrrole (JP-A-61-240625), polythiophene derivative (JP-A-2-15611(U.S. Pat. No. 4,910,645)), and polyisothianaphthene (JP-A-62-118511).Many of these electrically conducting polymers comprising a π-conjugatedsystem are used as a composition containing a dopant. Further, recently,not only dopants are used singly but also they are used in combinationwith manganese dioxide (JP-B-6-101418 (the term “JP-B” as used hereinmeans publication of examined Japanese patent application) (U.S. Pat.No. 4,959,753)) or a filler (JP-A-9-320901).

[0007] Thus, the reason why electrically conducting polymers are drawingan attention as the solid electrolyte is that they may be improved tohave a sufficiently high electric conductivity. However, there is aproblem in that if the electric conductivity is higher than a properrange, the leakage current greatly increases to cause short circuit,whereas if it is lower than the proper range, the frequency propertiesare deteriorated to cause a large reduction in the capacity.Accordingly, it is a subject of development how to control the electricconductivity of the solid electrolyte in a proper range and attain theheat resistance and thermal stability thereof.

[0008] On the other hand, as the method for forming a solid electrolytelayer, there have hitherto been known a method of forming by fusion asolid electrolyte layer on a dielectric layer of a valve acting metalsurface having a microfine porous or void structure and a method ofproducing the above-mentioned electrically conducting polymer on adielectric layer. More specifically, for example, in the case of using apolymer of a 5-membered heterocyclic compound such as pyrrole orthiophene, there have been known a method where an anode foil is dippedin a solution of a 5-membered heterocyclic compound in a loweralcohol/water, and then dipped in an aqueous solution having dissolvedtherein an oxidizing agent and an electrolyte to give rise to chemicalpolymerization, thereby forming an electrically conducting compound(JP-A-5-175082), and a method where a 3,4-dioxyethylenethiophene monomerand an oxidizing agent each preferably in the form of a solution areapplied separately differing in time or simultaneously on an oxide coverlayer of a metal foil to thereby form a solid electrolyte layer(JP-A-2-15611 (U.S. Pat. No. 4,910,645) and JP-A-10-32145 (EuropeanPatent Application Laid-open No. 820076(A2)). In particular,JP-A-10-32145 (European Patent Application Laid-open No. 820076(A2))discloses polymers of a monomer selected from pyrrole, thiophene, furan,aniline and derivatives thereof and doped with an aromatic polysulfonicacid having a plurality of sulfonic acid groups in the molecularstructure and also discloses as a production method, a polymerizationmethod in which a monomer is introduced after a mixed solution of theabove-mentioned monomer and an oxidizing agent is coated and dried orafter an oxidizing agent is introduced. Also, JP-A-10-32145 (EuropeanPatent Application Laid-open No. 820076(A2)) discloses a productionmethod in which the dopant of the aromatic polysulfonic acid is utilizedas a constituent component of the oxidizing agent (ferric salt) anddescribes that the solid electrolytic capacitor provided therewith hasan advantage that it is excellent in high temperature resistance andprevention of deterioration of static capacity. As the oxidizing agentused in the prior art in the case of chemical polymerization of5-membered aromatic cyclic compounds, for example, thiophene, there havebeen known iron (III) chloride, Fe(ClO₄)₃, organic acid iron (III) salt,inorganic acid iron (III) salt, alkyl persulfate, ammonium persulfate(hereafter, abbreviated as APS), hydrogen peroxide, K₂Cr₂O₇, etc.(JP-A-2-15611 (U.S. Pat. No. 4,910,645)), cupric compounds, silvercompounds, etc. (JP-A-10-32145 (European Patent Application Laid-openNo. 820076(A2)).

[0009] More specifically, the capacitor comprising a solid electrolyteof the manganese dioxide is disadvantageous in that the oxide layer isruptured at the thermal decomposition of manganese nitrate and theimpedance property is unsatisfactory. Use of lead dioxide must beaccompanied with a consideration on the environment.

[0010] The solid electrolytic capacitor using a tetracyanoquinodimethane(TCNQ) complex salt has good heat fusion workability and excellentelectric conductivity but the TCNQ complex salt itself is said to have aproblem in the heat resistance and in turn, a poor reliability in thesoldering heat resistance.

[0011] In order to overcome these problems, the above-mentionedelectrically conducting polymer such as polypyrrole is applied to thesolid electrolyte on a dielectric surface by electrochemicalpolymerization or chemical polymerization but the conventionalcapacitors with electrically conducting polymer such as polypyrrole hasa problem that their capacitor characteristics vary greatly depending onthe humidity resistance load.

[0012] Further, as associated with humidity resistance load, heatresistance is highly demanded. For example, soldering heat resistance(reflow characteristic) when a capacitor element is molded into acapacitor component is laid importance so that a capacitor elementhaving a high heat resistance is demanded.

[0013] The electrically conducting polymer layer as a solid electrolytemust have a high conductivity and be a heat resistant material which canbe formed so as to cover all the inner surfaces of the pore cavitiesinside the anode and endure the above-mentioned soldering temperature.In addition, the following conditions are required therefor.

[0014] That is, firstly, it can relax thermal stress generated bysoldering, etc., secondly it has good adhesion both mechanically andelectrically with an electrically conducting paste layer formed on theelectrically conducting polymer layer, and thirdly it has a good abilityof repairing an oxide dielectric film when it is conducted electrically.

[0015] With respect to the first condition of relaxation of thermalstress, it has been proposed to form an electrically conducting polymerlayer having a certain thickness on the outer surface of anode on whichan oxide dielectric film has been formed. To achieve this, there havebeen disclosed a method in which a first electrically conducting polymerlayer which serves as a precoat layer is formed by chemicalpolymerization and then a second electrically conducting polymer layeris formed by electrolytic polymerization using the first polymer layeras an electrode (JP-A-63-173313 (U.S. Pat. No. 4,780,796) and a methodin which a solution of electrically conducting polymer containing afiller is coated to form an electrically conducting polymer layer(JP-A-9-320901). The ability of relaxing thermal stress is influencednot only by the thickness of the layer but also by the structure of thelayer. As the electrically conducting polymer having a differentmacroscopic structure, there has been disclosed a sponge-likeelectrically conducting polymer molded article containing theelectrically conducting polymer as a continuous phase (JP-A-8-53566).

[0016] With respect to the improvement in the adhesion between thesecond electrically conducting polymer layer and the electricallyconducting paste layer, it has been proposed to form unevenness on thesurface of the electrically conducting polymer layer. To achieve this;there have been disclosed a method in which a solution having mixedtherein microfine powder is coated as it is on a first electricallyconducting polymer layer to provide the microfine powder and then asecond electrically conducting polymer layer is formed thereon(JP-A-7-94368 (U.S. Pat. No. 5,473,503)) and a method in which microfineelectrically conducting polymer powder is injected or sprayed ascontained in a gas or liquid flow on a first electrically conductingpolymer layer and then a second electrically conducting polymer layer isformed thereon (JP-A-9-320898 (European Patent Application Laid-open No.825626(A2)).

[0017] With respect to the improvement in the ability of repairing oxidedielectric film as the third point, a method has been disclosed in whicha tantalum solid electrolytic capacitor has a structure that has anelectrically conducting polymer compound covers an oxide dielectric filmso that cavities remain in the pores and is provided with an oxygensource to enable insulation of the electrically conducting polymercompound upon electric conduction (JP-A-7-122464 (U.S. Pat. No.5,455,736)).

[0018] As stated above, the conventional electrically conductingpolymers are insufficient in heat resistance.

[0019] Also, the method proposed for the relaxation of thermal stress isdisadvantageous in that the electrically conducting polymer layer formedby electrolytic polymerization has less surface unevenness and theadhesion with the electrically conducting paste layer is poor. In themethod of forming an electrically conducting polymer layer having acertain thickness by coating an electrically conducting polymer solutioncontaining a filler (JP-A-9-320901), the ability of relaxing thermalstress per thickness of the polymer layer is low so that the polymerlayer has to have a relatively large thickness, which is disadvantageousfor the down-sizing and increasing capacity of the device.

[0020] The sponge-like electrically conducting polymer molded article(JP-A-8-53566) is not applied to a solid electrolytic capacitor and theproduction method for the sponge-like electrically conducting polymermolded article according to the invention described in this prior art isa method in which an electrically conducting polymer solution is cooledto freeze the solvent and carry out polymerization and thereafter thesolvent is removed by freeze-drying or thawing and hence its operationis cumbersome and further the oxide dielectric film tends to sufferdamages upon freezing and thawing, so that it cannot be said to be amethod which is applicable to solid electrolytic capacitors.

[0021] Next, with respect to the proposal for improving the adhesionwith the electrically conducting paste layer by forming unevenness onthe surface of the electrically conducting polymer layer, the method inwhich a solution having mixed therein microfine powder is coated as itis on a first electrically conducting polymer layer to provide themicrofine powder (JP-A-7-94368 (U.S. Pat. No. 5,473,503)) has a problemthat the conditions of forming unevenness fluctuate in a device or lotor between lots. Also, the method in which microfine powder of anelectrically conducting polymer is injected or sprayed as contained in agas or liquid flow on a first electrically conducting polymer layer(JP-A-9-320898 (European Patent Application Laid-open No. 825626(A2))has a problem that the ability of relaxing thermal stress per thicknessof the polymer layer is low so that the polymer layer is required tohave a relatively large thickness, which is disadvantageous for thedown-sizing and increasing capacity of the device.

[0022] Further, a proposal has been made to improve the ability ofrepairing the oxide dielectric film. In the method in which anelectrically conducting polymer compound covers the oxide dielectricfilm with leaving cavities in the pores (JP-A-7-122464 (U.S. Pat. No.5,455,736)), the ratio of cavities in the pores is adjusted byrepetition of oxidative polymerization so that when formation of a thicklayer of electrically conducting polymer on the outer surface of theanode is contemplated the cavities already existing in the pores tend tobe closed. Therefore, there is a problem that the formation of anelectrically conducting polymer layer having a certain thickness on theouter surface and securing cavities in the pores are not fulfilledsimultaneously. Also there is a problem that failure of formingunevenness on the surface of the polymer layer results in a pooradhesion with the electrically conducting paste layer.

[0023] As described above, upon the production of a capacitor, furtherimprovements are required on the material for the solid electrolyte,production method thereof, heat stability, homogeneity of the film andthe like.

[0024] Under these circumstances, an object of the present invention isto provide a solid electrolytic capacitor having excellent heatresistance comprising an electrically conducting polymer layer excellentin the ability of relaxing thermal stress, adhesion with an electricallyconducting paste layer, ability of repairing an oxide dielectric film.

[0025] Also, an object of the present invention is to provide acapacitor satisfying the requirements with respect to the reduction inthe weight, high capacity, high frequency property, tan δ, leakagecurrent, heat resistance (reflow property), durability, etc.

[0026] Further, an object of the present invention is to provide amethod for the production of an electrolytic capacitor having theabove-mentioned properties and thereby providing a solid electrolyticcapacitor which is excellent in not only initial properties such as lossfactor, leakage current, heat resistance, equivalent series resistanceand impedance in high frequency regions but also durability in asparking voltage test, long-term reliability (durability under hightemperature and high humidity conditions, etc.).

DISCLOSURE OF THE INVENTION

[0027] The present inventors have made intensive research on thechemical structure and lamellar structure of an electrically conductingpolymer layer as a solid electrolyte with view to achieving theabove-mentioned objects and as a result they have found that use of anelectrically conducting polymer having a lamellar structure can solvethe problems of ability of relaxing thermal stress, etc.

[0028] That is, as a result of intensive research on the kind,combination, content, etc. of dopant anions in the electricallyconducting polymer composition as the solid electrolyte, it has now beenfound that a high performance solid electrolytic capacitor which issmall in size, has a low impedance and exhibits durability in a sparkingvoltage test can be obtained by providing a solid electrolytic capacitorcomprising opposite electrodes, a dielectric layer having porescomprised by a metal oxide on a surface of a valve acting metal foil asone of electrodes, and a solid electrolyte comprised by an electricallyconducting polymer compound with (1) a sulfoquinone having at least onesulfoanion group and a quinone structure in the molecule and an anionother than the sulfoquinone, having a dopant function in combination inthe solid electrolyte or (2) at least one anthracene monosulfonic acidselected from anthracenesulfonic acid or derivatives thereof having asulfonic acid group as a dopant in the solid electrolyte.

[0029] Based on the above-described findings, the present inventionprovides the following solid electrolytic capacitors and methods for theproduction of the same.

[0030] (1) A solid electrolytic capacitor comprising a valve actingmetal having pores, a dielectric film formed on a surface of the valveacting metal, and a solid electrolyte layer provided on the dielectricfilm, wherein at least a portion of the solid electrolyte layer is of alamellar structure.

[0031] (2) The solid electrolytic capacitor described in (1) above, inwhich the solid electrolyte layer is formed on an outer surface of thedielectric film or on the outer surface and inside the pores.

[0032] (3) The solid electrolytic capacitor as described in (1) or (2)above, in which at least a portion of interlayer portion in the lamellarstructure comprises a space portion.

[0033] (4) The solid electrolytic capacitor as described in any one of(1) to (3) above, in which each unit layer of the solid electrolyteconstituting the lamellar structure has a thickness in the range of0.01-5 μm and a total thickness of the solid electrolyte layer is in therange of 1-200 μm.

[0034] (5) The solid electrolytic capacitor as described in any one of(1) to (4) above, in which the solid electrolyte layer comprises acomposition containing a π-electron conjugated system polymer and/orother electrically conducting polymer.

[0035] (6) The solid electrolytic capacitor as described in (5) above,in which the electrically conducting polymer comprises as a repeatingunit a structural unit represented by general formula (I) below

[0036] (wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6(meaning 1 to 6 carbon atoms, hereafter the same) alkyl group, a linearor branched, saturated or unsaturated C1-6 alkoxy group, a hydroxylgroup, a halogen atom, a nitro group, a cyano group, a trihalomethylgroup, a phenyl group and a substituted phenyl group, R¹ and R² may becombined to each other at any position to form at least one divalentchain for forming at least one 5-, 6- or 7-membered saturated orunsaturated ring structure, X represents a hetero atom selected from S,O, Se, Te or NR³, R³represents a hydrogen atom, a linear or branched,saturated or unsaturated C1-6 alkyl group, a phenyl group or a linear orbranched, saturated or unsaturated C1-6 alkoxy, the alkyl group and thealkoxy group represented by R¹, R² or R³may optionally contain in thechain thereof a carbonyl bond, an ether bond, an ester bond, an amidebond or an imino bond, and δ represents a number of from 0 to 1).

[0037] (7) The solid electrolytic capacitor as described in (5) above,in which the electrically conducting polymer comprises as a repeatingunit a structural unit represented by general formula (II) below

[0038] (wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedstructure containing the two oxygen elements shown in the formula bycombining the C1-6 alkylene groups to each other at any position, thering structure formed in the scope thereof includes a chemical structuresuch as a vinylene group which may be substituted and a phenylene groupwhich may be substituted, and δ represents a number of from 0 to 1).

[0039] (8) The solid electrolytic capacitor as described in (5) above,in which the electrically conducting polymer is a condensedheteropolycyclic polymer comprising as a repeating unit a structuralunit represented by general formula (III) below

[0040] (wherein the substituents R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ eachindependently represents a monovalent group selected from the groupconsisting of a hydrogen atom, a linear or branched, saturated orunsaturated C1-10 alkyl, alkoxy or alkyl ester group, a halogen atom, anitro group, a cyano group, a primary, secondary or tertiary aminogroup, a trihalomethyl group, a phenyl group and a substituted phenylgroup, the alkyl chains of R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ may combine toeach other at any position to form at least one divalent chain forforming at least one 3-, 4-, 5-, 6- or 7-membered saturated orunsaturated hydrocarbon cyclic structure together with the carbon atomsto which the substituents are bonded, the alkyl group, the alkoxy groupor the alkyl ester group of R⁶, R⁷, R⁸, R⁹, R¹⁰ or R¹¹ or the cyclichydrocarbon chain formed by the substituents may contain any number ofany of carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl andimino bonds, k represents a number of the condensed ring enclosed by thethiophene ring and the benzene ring having substituents R⁶ to R⁹ andrepresents an integer of from 0 to 3 excluding a form in which all of R⁶to R⁹ represent a hydrogen atom from among derivatives in which k=0, andthe condensed ring may optionally contain 1 to 2 nitrogen atoms (N) orN-oxide, δ is in the range of 0 to 1, Z represents an anion, j is avalency of Z and is 1 or 2.)

[0041] (9) The solid electrolytic capacitor as described in (8) above,in which the condensed heteropolycyclic polymer represented by generalformula (III) is a condensed heteropolycyclic polymer comprisingrepresented by general formula (IV) below where k=0

[0042] (wherein R⁶, R⁷, R⁸, R⁹, δ, Z and j are the same as in formula(III), and the condensed ring may optionally contain 1 to 2 nitrogenatoms (N) or N-oxide).

[0043] (10) The solid electrolytic capacitor as described in (9) above,in which the condensed heteropolycyclic polymer represented by generalformula (IV) above is a condensed heteropolycyclic polymer selected from5,6-dioxymethylene-isothianaphthenylene polymer and and5,6-dimethoxy-isothianaphthenylene polymer.

[0044] (11) The solid electrolytic capacitor as described in (8) above,in which the condensed heteropolycyclic polymer represented by generalformula (III) is a condensed heteropolycyclic polymer comprisingrepresented by general formula (V) below where k=1

[0045] (wherein R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, δ, Z and j are the same as informula (III), and the condensed ring may optionally contain 1 to 2nitrogen atoms (N) or N-oxide).

[0046] (12) The solid electrolytic capacitor as described in (5) above,in which the electrically conducting polymer is an electricallyconducting polythiophene and the composition containing the electricallyconducting polythiophene contains a sulfate ion in the range of 0.1-10mol % and a naphthalenesulfonate ion in the range of 1-50 mol %.

[0047] (13) The solid electrolytic capacitor as described in (12) above,in which the electrically conducting polythiophene contains as arepeating unit the structural unit represented by general formula (II)described in (7) above.

[0048] (14) The solid electrolytic capacitor as described in (12) or(13) above, in which the sulfate ion is derived from a reduced form ofpersulfate.

[0049] (15) A solid electrolytic capacitor comprising a valve actingmetal having pores, a dielectric film formed on a surface of the valveacting metal, and a solid electrolyte layer comprising an electricallyconducting polymer composition layer provided on the dielectric film, inwhich the composition contains sulfoquinone anion having at least onesulfo anion group and a quinone structure in the molecule in an amountof 0.1-50 mol % and an anion other than the sulfoquinone anion in therange of 0.1-10 mol %.

[0050] (16) The solid electrolytic capacitor as described in (15) above,in which a main chain of the electrically conducting polymer in thecomposition contains a structural unit represented by general formula(I) below

[0051] (wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6alkyl, a linear or branched, saturated or unsaturated C1-6 alkoxy group,a hydroxyl group, a halogen atom, a nitro group, a cyano group, atrihalomethyl group, a phenyl group and a substituted phenyl group, R¹and R²may be combined to each other at any position to form at least onedivalent chain for forming at least one 5-, 6- or 7-membered saturatedor unsaturated ring structure, X represents a hetero atom selected fromS, O, Se, Te or NR³, R³ represents H, a linear or branched, saturated orunsaturated C1-6 alkyl group, a phenyl group or a linear or branched,saturated or unsaturated C1-6 alkoxy group, the alkyl group and thealkoxy group represented by R¹, R² or R³may optionally contain in thechain thereof a carbonyl bond, an ether bond, an ester bond, an amidebond or an imino bond, and δ represents a number of from 0 to 1).

[0052] (17) The solid electrolytic capacitor as described in (16) above,in which the structural unit represented by formula (I) is a chemicalstructure represented by the following formula (II):

[0053] (wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedheterocyclic structure containing the two oxygen elements shown in theformula by combining the C1-6 alkyl groups to each other at anyposition, the ring structure formed in the scope thereof includes achemical structure such as a vinylene group which may be substituted anda substituted phenylene group which may be substituted, and δ representsa number of from 0 to 1).

[0054] (18) The solid electrolytic capacitor as described in any one of(15) to (17), in which a base structure of the sulfoquinone anion is atleast one selected from the group consisting of p-benzoquinone,o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone,2,6-naphthoquinone, 9,10-anthraquinone, 1,4-anthraquinone,1,2-anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone,6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone,camphorquinone, 2,3-bornadione, 9,10-phenanthrenequinone, and2,7-pyrenequinone.

[0055] (19) The solid electrolytic capacitor as described in (18) above,in which the sulfoquinone contains in the molecule thereof asulfoquinone having at least one sulfoanion group and a quinonestructure and a hydroquinone structure and/or quinhydrone structurethereof produced from the sulfoquinone.

[0056] (20) The solid electrolytic capacitor as described in any of (15)to (19) above, in which the anion other than the sulfoquinone anion is areduced form anion of an oxidizing agent.

[0057] (21) The solid electrolytic capacitor as described in (20) above,in which the reduced form anion of an oxidizing agent is a sulfate ion.

[0058] (22) A solid electrolytic capacitor comprising a valve actingmetal having pores, a dielectric film formed on a surface of the valveacting metal, and a solid electrolyte layer comprising an electricallyconducting polymer composition layer provided on the dielectric film, inwhich the composition contains at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having a sulfonate group orderivatives thereof as a dopant.

[0059] (23) The solid electrolytic capacitor as described in (22) above,in which the solid electrolytic capacitor as described in (22) above, inwhich the anthracenemonosulfonate anion is contained in the range of0.1-50 mol % of total repeating unit of the electrically conductingpolymer.

[0060] (24) The solid electrolytic capacitor as described in (22) or(23) above, which contains in addition to the anthracene monosulfonateanion a reduced form anion of an oxidizing agent in the range of 0.1-10mol %.

[0061] (25) The solid electrolytic capacitor as described in (24) above,in which the reduced form anion of an oxidizing agent is a sulfate ion.

[0062] (26) The solid electrolytic capacitor as described in any one of(22) to (25) above, in which the anthracenesulfonic acid derivative isanthracenemonosulfonic acid of which at least one of hydrogen atoms onan anthracene ring is substituted by a C1-12 linear or branched,saturated or unsaturated alkyl group or alkoxy group.

[0063] (27) The solid electrolytic capacitor as described in (22) above,in which a main chain of the electrically conducting polymer in thecomposition contains a structural unit represented by general formula(I) below

[0064] (wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6alkyl, a linear or branched, saturated or unsaturated C1-6 alkoxy group,a hydroxyl group, a halogen atom, a nitro group, a cyano group, atrihalomethyl group, a phenyl group and a substituted phenyl group, R¹and R²may be combined to each other at any position to form at least onedivalent chain for forming at least one 5-, 6- or 7-membered saturatedor unsaturated ring structure, X represents a hetero atom selected fromS, O, Se, Te or NR³, R³represents H, a linear or branched, saturated orunsaturated C1-6 alkyl group, a phenyl group or an alkoxy group having alinear or branched, saturated or unsaturated C1-6 hydrocarbon group, thealkyl group and the alkoxy group represented by R¹, R² or R³ mayoptionally contain in the chain thereof a carbonyl bond, an ether bond,an ester bond, an amide bond or an imino bond, and δ represents a numberof from 0 to 1).

[0065] (28) The solid electrolytic capacitor as described in (27) above,in which the structural unit represented by formula (I) is a chemicalstructure represented by the following formula (II):

[0066] (wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedcyclic structure containing the two oxygen elements shown in the formulaby combining the C1-6 alkyl groups to each other at any position, thering structure formed in the scope thereof includes a chemical structuresuch as a vinylene group which may be substituted and a substitutedphenylene group which may be substituted, and δ represents a number offrom 0 to 1).

[0067] (29) A method for producing a solid electrolytic capacitor asdescribed in (1) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer provided on the dielectric film, the methodcomprising polymerizing a condensed heteropolycyclic compoundrepresented by the following formula (VI):

[0068] (wherein the substituents R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ eachindependently represents a monovalent group selected from the groupconsisting of H, a linear or branched, saturated or unsaturated C1-10alkyl, alkoxy or alkylester group, a halogen, a nitro group, a cyanogroup, a primary, secondary or tertiary amino group, a trihalomethylgroup, a phenyl group and a substituted phenyl group, the alkyl chainsof R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ may combine to each other at any positionto form at least one divalent chain for forming at least one 3-, 4-, 5-,6- or 7-membered saturated or unsaturated hydrocarbon cyclic structuretogether with the carbon atoms to which the substituents are bonded, thealkyl group, the alkoxy group or the alkylester group of R⁶, R⁷, R⁸, R⁹,R¹⁰ or R¹¹ or the cyclic hydrocarbon chain formed by the substituentsmay contain any of carbonyl, ether, ester, amide, sulfide, sulfinyl,sulfonyl and imino bonds, k represents a number of the condensed ringenclosed by the thiophene ring and the benzene ring having substituentsR⁶ to R⁹ and represents an integer of from 0 to 3, and the condensedring may optionally contain nitrogen or N-oxide) alone or together withanother anion having a dopant ability, on the dielectric film formed ona porous valve acting metal surface by the action of an oxidizing agentto form a solid electrolyte layer on the dielectric film.

[0069] (30) The method for producing a solid electrolytic capacitor, asdescribed in (29) above, in which as the condensed heteropolycycliccompound, there is used at least one member selected fromdihydroisothianaphthene, dihydronaphtho[2,3-c]thiophene anddihydrothieno[3,4-b]quinoxaline derivatives.

[0070] (31) The method for producing a solid electrolytic capacitor, asdescribed in (29) above, in which at least one member selected from1,3-dihydroisothianaphthene,5,6-dioxymethylene-1,3-dihydroisothianaphthene,5,6-dimethoxy-1,3-dihydroisothianaphthene,1,3-dihydronaphtho[2,3-c]thiophene and1,3-dihydrothieno[3,4-b]quinoxaline.

[0071] (32) A method for producing a solid electrolytic capacitor asdescribed in (1) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer provided on the dielectric film, the methodcomprising polymerizing a condensed heteropolycyclic compoundrepresented by the following formula (VII):

[0072] (wherein the substituents R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ and k havethe same meanings as in general formula (VI) described in (29) above,and the condensed ring may optionally contain 1 to 2 nitrogen atoms (N)or N-oxide) alone or together with another anion having a dopantability, on the dielectric film formed on a porous valve acting metalsurface by the action of an oxidizing agent to form a solid electrolytelayer on the dielectric film.

[0073] (33) The method for producing a solid electrolyte as described in(32) above, in which as the condensed heteropolycyclic compound, thereis used at least one member selected fromdihydroisothianaphthene-2-oxide, dihydronaphtho[2,3-c]thiophene-2-oxideand dihydrothieno[3,4-b]quinoxaline-2-oxide derivatives.

[0074] (34) The method for producing a solid electrolytic capacitor, asdescribed in (32) above, in which at least one member selected from1,3-dihydroisothianaphthene-2-oxide,5,6-dioxymethylene-1,3-dihydroisothianaphthene-2-oxide,5,6-dimethoxy-1,3-dihydroisothianaphthene-2-oxide,1,3-dihydronaphtho[2,3-c]thiophene-2-oxide and1,3-dihydrothieno[3,4-b]quinoxaline-2-oxide.

[0075] (35) A method for producing a solid electrolytic capacitor asdescribed in (1) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and anelectrically conducting polythiophene composition as a solid electrolyteprovided on the dielectric film, the method comprising polymerizing athiophene monomer represented by the following formula (IX):

[0076] (wherein R⁴ and R⁵ have the same meanings as defined in (17)above) in the presence of naphthalenesulfonate anion by the action of apersulfate to form a solid electrolyte layer on the dielectric film.

[0077] (36) The method for producing a capacitor as described in (35)above, in which the persulfate is ammonium persulfate or potassiumpersulfate.

[0078] (37) The method for producing a capacitor as described in any oneof (29) to (36) above, in which the polymerization by the action of anoxidizing agent within the metal oxide pores in the dielectric layer isrepeated at least twice.

[0079] (38) A method for producing a capacitor as described in (15)above comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an-electrically conducting polymer composition layerprovided on the dielectric film, in which the method comprisespolymerizing a monomer compound represented by the following formula(VIII):

[0080] (wherein R¹, R² and X have the same meanings as defined in (16)above) in the presence of a compound which donates a sulfoquinone anionby the action of an oxidizing agent to form a solid electrolyte layer.

[0081] (39) The method for producing a solid electrolytic capacitor asdescribed in (38) above, in which the monomer compound represented bygeneral formula (VIII) above is a compound represented by the followinggeneral formula (IX):

[0082] (wherein R⁴ and R⁵ have the same meanings as defined in (17)above).

[0083] (40) A method for producing a solid electrolytic capacitor asdescribed in (15) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer comprising an electrically conducting polymercomposition provided on the dielectric film, the method comprisingpolymerizing a monomer by the action of an oxidizing agent to form asolid electrolyte layer on the dielectric film,

[0084] in which the method comprises the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing a monomer compound, and dipping in a solutioncontaining an oxidizing agent and a sulfoquinone anion.

[0085] (41) The method for producing a solid electrolytic capacitor asdescribed in (40) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing amonomer compound and then in a solution containing an oxidizing agentand a sulfoquinone anion.

[0086] (42) The method for producing a solid electrolytic capacitor asdescribed in (43) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and then dipping the metal in a solutioncontaining an oxidizing agent and a sulfoquinone anion.

[0087] (43) The method for producing a solid electrolytic capacitor asdescribed in (42) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and then dipping the metal in a solutioncontaining an oxidizing agent and a sulfoquinone anion, followed bywashing and drying.

[0088] (44) The method for producing a solid electrolytic capacitor asdescribed in (40) above, in which the method comprises the step ofdipping the valve acting metal having formed thereon the dielectric filmin a solution containing an oxidizing agent and a sulfoquinone anion andthen dipping the metal in a solution containing a monomer compound.

[0089] (45) The method for producing a solid electrolytic capacitor asdescribed in (44) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film in a solution containingan oxidizing agent and a sulfoquinone anion and then dipping the metalin a solution containing a monomer compound.

[0090] (46) The method for producing a solid electrolytic capacitor asdescribed in (45) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film in a solution containingan oxidizing agent and a sulfoquinone anion and then dipping the metalin a solution containing a monomer compound, followed by washing anddrying.

[0091] (47) A method for producing a solid electrolytic capacitor asdescribed in (15) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer comprising an electrically conducting polymercomposition provided on the dielectric film, the method comprisingpolymerizing a monomer by the action of an oxidizing agent to form asolid electrolyte layer on the dielectric film,

[0092] in which the method comprises the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing an oxidizing agent and of dipping the metal in asolution containing a monomer compound and a sulfoquinone anion.

[0093] (48) The method for producing a solid electrolytic capacitor asdescribed in (47) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing anoxidizing agent and then in a solution containing a monomer compound anda sulfoquinone anion.

[0094] (49) The method for producing a solid electrolytic capacitor asdescribed in (48) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining an oxidizing agent and then dipping the metal in a solutioncontaining a monomer compound and a sulfoquinone anion.

[0095] (50) The method for producing a solid electrolytic capacitor asdescribed in (49) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining an oxidizing agent and then dipping the metal in a solutioncontaining a monomer compound and a sulfoquinone anion, followed bywashing and drying.

[0096] (51) The method for producing a solid electrolytic capacitor asdescribed in (47) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing amonomer, compound and a sulfoquinone anion and then in a solutioncontaining an oxidizing agent.

[0097] (52) The method for producing a solid electrolytic capacitor asdescribed in (51) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and a sulfoquinone anion and then dippingthe metal in a solution containing an oxidizing agent.

[0098] (53) The method for producing a solid electrolytic capacitor asdescribed in (52) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and a sulfoquinone anion and then dippingthe metal in a solution containing an oxidizing agent, followed bywashing and drying.

[0099] (54) The method for producing a solid electrolytic capacitor asdescribed in any one of (38) to (53) above, in which the oxidizing agentis a persulfate.

[0100] (55) The method for producing a solid electrolytic capacitor asdescribed in any one of (40) to (53) above, in which the oxidizing agentis a persulfate and the monomer compound is a compound represented bythe following general formula (VIII)

[0101] (wherein R¹, R² and X have the same meanings as defined in (16)above).

[0102] (56) The method for producing a solid electrolytic capacitor asdescribed in (55) above, in which the monomer compound represented bythe general formula (VIII) above is a compound represented by thefollowing general formula (IX)

[0103] (wherein R⁴ and R⁵ have the same meanings as defined in (17)above).

[0104] (57) A method for producing a capacitor as described in (22)above comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an electrically conducting polymer composition layerprovided on the dielectric film, the method comprising polymerizing amonomer compound by the action of an oxidizing agent on the oxidedielectric film, in which the compound represented by the followingformula (VIII):

[0105] (wherein R¹, R² and X have the same meanings as defined in (27)above) is polymerized in the presence of a compound which donates atleast one anthracenemonosulfonate anion selected from anthracenesulfonicacid and derivatives thereof to form a solid electrolyte layer.

[0106] (58) The method for producing a solid electrolytic capacitor asdescribed in (57) above, in which the monomer compound represented bygeneral formula (VIII) above is a compound represented by the followinggeneral formula (IX):

[0107] (wherein R⁴ and R⁵ have the same meanings as defined in (28)above).

[0108] (59) A method for producing a solid electrolytic capacitor asdescribed in (22) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer comprising an electrically conducting polymercomposition provided on the dielectric film, the method comprisingpolymerizing a monomer by the action of an oxidizing agent to form asolid electrolyte layer on the dielectric film,

[0109] in which the method comprises the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing a monomer compound, and dipping in a solutioncontaining an oxidizing agent and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof.

[0110] (60) The method for producing a solid electrolytic capacitor asdescribed in (59) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing amonomer compound and then in a solution containing an oxidizing agentand at least one anthracenemonosulfonate anion selected fromanthracenesulfonic acid having one sulfonate group and derivativesthereof.

[0111] (61) The method for producing a solid electrolytic capacitor asdescribed in (60) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and then dipping the metal in a solutioncontaining an oxidizing agent and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof.

[0112] (62) The method for producing a solid electrolytic capacitor asdescribed in (61) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and then dipping the metal in a solutioncontaining an oxidizing agent and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof, followed by washing and drying.

[0113] (63) The method for producing a solid electrolytic capacitor asdescribed in (59) above, in which the method comprises the step ofdipping the valve acting metal having formed thereon the dielectric filmin a solution containing an oxidizing agent and at least oneanthracenemonosulfonate anion selected from anthracenesulfonic acidhaving one sulfonate group and derivatives thereof and then dipping themetal in a solution containing a monomer compound.

[0114] (64) The method for producing a solid electrolytic capacitor asdescribed in (63) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film in a solution containingan oxidizing agent and at least one anthracenemonosulfonate anionselected from anthracenesulfonic acid having one sulfonate group andderivatives thereof and then dipping the metal in a solution containinga monomer compound.

[0115] (65) The method for producing a solid electrolytic capacitor asdescribed in (64) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film in a solution containingan oxidizing agent and at least one anthracenemonosulfonate anionselected from anthracenesulfonic acid having one sulfonate group andderivatives thereof and then dipping the metal in a solution containinga monomer compound, followed by washing and drying.

[0116] (66) A method for producing a solid electrolytic capacitor asdescribed in (22) above comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer comprising an electrically conducting polymercomposition provided on the dielectric film, the method comprisingpolymerizing a monomer by the action of an oxidizing agent to form asolid electrolyte layer on the dielectric film,

[0117] in which the method comprises the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing an oxidizing agent and of dipping the metal in asolution containing a monomer compound and an anthracenemonosulfonateanion.

[0118] (67) The method for producing a solid electrolytic capacitor asdescribed in (66) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing anoxidizing agent and then in a solution containing a monomer compound andat least one anthracenemonosulfonate anion selected fromanthracenesulfonic acid having one sulfonate group and derivativesthereof.

[0119] (68) The method for producing a solid electrolytic capacitor asdescribed in (67) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining an oxidizing agent and then dipping the metal in a solutioncontaining a monomer compound and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof.

[0120] (69) The method for producing a solid electrolytic capacitor asdescribed in (68) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining an oxidizing agent and then dipping the metal in a solutioncontaining a monomer compound and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof, followed by washing and drying.

[0121] (70) The method for producing a solid electrolytic capacitor asdescribed in (66) above, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing amonomer compound and at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having one sulfonate group and derivativesthereof and then in a solution containing an oxidizing agent.

[0122] (71) The method for producing a solid electrolytic capacitor asdescribed in (70) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof and then dipping the metal in a solutioncontaining an oxidizing agent.

[0123] (72) The method for producing a solid electrolytic capacitor asdescribed in (71) above, in which the method comprises the step ofrepeating in a plurality of times the steps of dipping the valve actingmetal having formed thereon the dielectric film layer in a solutioncontaining a monomer compound and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof and then dipping the metal in a solutioncontaining an oxidizing agent, followed by washing and drying.

[0124] (73) The method for producing a solid electrolytic capacitor asdescribed in any one of (59) to (72), in which the monomer compound is acompound represented by the following general formula (VIII)

[0125] (wherein R¹, R² and X have the same meanings as defined in (27)above).

[0126] (74) The method for producing a solid electrolytic capacitor asdescribed in (73), in which the monomer compound represented by thefollowing general formula (VIII) is a compound represented by thefollowing general formula (IX)

[0127] (wherein R⁴ and R⁵ have the same meanings as defined in (28)above).

[0128] (75) The method for producing a solid electrolytic capacitor asdescribed in any one of (57) to (74) above, in which the oxidizing agentis a persulfate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0129]FIG. 1 is a vertical cross-sectional view showing an embodiment ofa solid electrolytic capacitor.

[0130]FIG. 2 is a scanning electron micrograph (at a magnification of×2,000) illustrating in cross section an aluminum foil with a porestructure having formed thereon an electrically conducting polymer layeraccording to Example 1 of the invention.

[0131]FIG. 3 is an enlarged scanning electron micrograph (at amagnification of ×10,000) with an outside surface portion of the porestructure illustrated in FIG. 2 on an enlarged scale.

[0132]FIG. 4 is an enlarged scanning electron micrograph (at amagnification of ×50,000) with an outside surface portion of the porestructure illustrated in FIG. 3 on an enlarged scale.

DETAILED DESCRIPTION OF THE INVENTION

[0133] The valve acting metal used in the solid electrolytic capacitorof the present invention includes elemental metal such as aluminum,tantalum, titanium, niobium, zirconium, magnesium, and silicon andalloys thereof. Their form may be in any form as far as they are formedarticle having pores such as an etched rolled foil and a fine powdersintered body.

[0134] The valve acting metal has formed thereon a dielectric filmcomposed of an oxide.

[0135] One of the solid electrolytic capacitors of the present inventionhas in at least a portion thereof a lamellar structure so that theability of relaxing thermal stress can be provided.

[0136] The solid electrolyte layer is formed inside pores and outersurface thereof on the dielectric layer on the surface of the valveacting metal. The thickness of the outer surface layer is in the rangeof 1-200 μm, preferably 1-100 μm. In the present invention, many of theabove-mentioned lamellar structures are formed on the outer surface butit is desirable that it is also formed inside the pores. The directionin which the layers are arranged is such that many layers are arrangedsubstantially parallel to the valve acting metal surface. In at least apart between adjacent layers, there is formed a space portion. Thethickness per unit layer constituting the lamellar structure is in therange of 0.01-5 μm, preferably 0.01-1 μm, more preferably 0.1 to 0.3 μm.

[0137] The solid electrolyte used in the solid electrolytic capacitor ofthe present invention is preferably a π-electron conjugated polymer orother polymers and complex of these. In particular, a π-electronconjugated polymer or a polymer containing it is preferred.

[0138] As the π-electron conjugated polymer, preferred is a polymerrepresented by the general formula (I) above

[0139] (wherein the symbols have the same meanings as defined above).

[0140] In the general formula (I), the substituents R¹, R² and R³ when xis NR³, independently a linear or branched, saturated or unsaturatedC1-6 alkyl group. Specific examples thereof include methyl, ethyl,vinyl, propyl, allyl, isopropyl, butyl, and 1-butenyl. Specific examplesof the linear or branched, saturated or unsaturated C1-6 alkoxy groupinclude methoxy, ethoxy, propoxy, isopropoxy, and butoxy. Further, thesubstituents other than the alkyl group and alkoxy group include, forexample, a nitro group, a cyano group, a phenyl group and a substitutedphenyl group (halogen-substituted phenyl substituted with a halogen suchas Cl, Br, F, etc.). The alkyl group or alkoxy group represented by R¹or R² may optionally contain in the chain thereof a carbonyl bond, anether bond, an ester bond, an amide bond, or an imino bond, andparticularly useful examples include methoxyethoxy andmethoxyethoxyethoxy.

[0141] The above-mentioned substituents R¹ and R² may bond to each otherat any position to form a divalent group which forms at least one 5-, 6-or 7-membered saturated or unsaturated cyclic structure. Examples ofsuch a divalent group represented by the general formula (I) includes a3,4-propylene-substituted structure, a 3,4-butylene-substitutedstructure, a 3,4-butenylene-substituted structure, a3,4-butadienylene-substituted structure, and a naphtho[2,3-c] condensedstructure.

[0142] X represents a hetero atom. Specific examples thereof include S,O, Se, Te and NR³. The above-mentioned 3,4-butenylene-substitutedstructure in which X is S, when it assumes the chemical structurerepresented by the general formula (I), is also called as anisothianaphthenylene structure. Further, a naphtho[2,3-c] condensedstructure, when it assumes the chemical structure represented by thegeneral formula (I), is a naphtho[2,3-c]thienylene condensed structure.In the formulae, δ is a value in the range of 0 to 1.

[0143] The polymer represented by the general formula (I) above includespolymers represented by the following general formula (II)

[0144] (wherein the symbols have the same meanings as defined above).

[0145] Examples of the substituents represented by the general formula(II) include methyl, ethyl, propyl, isopropyl, vinyl, and allyl.Further, C1-6 alkyl groups represented by R⁴ and R⁵ may bond to eachother at any position to form a substituent group constituting at leastone cyclic structure of 5-, 6- or 7-membered saturated hydrocarboncontaining the two oxygen atoms described in the general formula (II)above, preferably 1,2-ethylene, 1,2-propylene, and 1,2-dimethylethylene.The above-mentioned cyclic structure includes those having a vinylenebond, those having a phenylene structure which may be substituted, forexample; 1,2-vinylene, 1,2-propenylene, 2,3-butylen-2-ene,1,2-cyclohexylene, methyl-o-phenylene, 1,2-dimethyl-o-phenylene, andethyl-o-phenylene.

[0146] The above-mentioned solid electrolytic capacitor of the presentinvention, which has a lamellar structure in at least a portion of solidelectrolyte on the dielectric layer and preferably is provided with anelectrically conducting polymer layer having a space portion in at leasta part of adjacent layers, can relax thermal stress efficiently. Also,preferably the solid electrolyte layer such as the electricallyconducting polymer formed on the outer surface of the valve acting metalhas a space portion therein so that the electrically conducting pastelayer can get into the space to give a good adhesion. Formation of aspace portion in the pores secures supply of oxygen to improve theability of repairing dielectric film upon electric conduction.

[0147] To form a lamellar structure and a space portion in the solidelectrolyte layer, for example, a method can be used in which the stepof supplying a monomer and an oxidizing agent and polymerizing them in apredetermined manner is repeated as shown in examples described later.As the oxidizing agent, there can be used Fe(III) base compounds such asFeCl₃, FeClO₄, and Fe (organic acid anion) salt, anhydrous aluminumchloride/cuprous chloride, alkali metal persulfates, ammoniumpersulfates, peroxides, manganese compounds such as potassiumpermanganate, quinones such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone(DDQ), and tetrachloro-1,4-benzoquinone, tetracyano-1,4-benzoquinone,halogens such as iodine and bromine, peracids, sulfuric acid, fumingsulfuric acid, sulfur trioxide, sulfonic acids such as chlorosulfuricacid, fluorosulfuric acid and amidosulfuric acid, ozone, etc., andcombinations of a plurality of the oxidizing agents.

[0148] Next, explanation will be made on the solid electrolyticcapacitor of the present invention having an increased soldering heatresistance. The capacitor uses a condensed heteropolycyclic polymerrepresented by the general formula (III)

[0149] (wherein the symbols have the same meanings as defined above).

[0150] The polymer represented by the general formula (III) is acondensed heteropolycyclic compound whose repeating unit is representedby the general formula (VI) above

[0151] (wherein the symbols have the same meanings as defined above).

[0152] The compound represented by the general formula (VI), morespecifically, is, for example, a derivative having1,3-dihydroisothianaphthene (also referred to as1,3-dihydrobenzo[c]thiophene) skeleton represented by the followinggeneral formula (X), i.e., k=0,

[0153] (wherein R⁶, R⁷, R⁸ and R⁹ have the same meanings as in thegeneral formula (VI), and the condensed ring in the formula mayoptionally contain nitrogen or N-oxide) or a derivative having1,3-dihydronaphtho[2,3-c]thiophene skeleton represented by the generalformula (XI), i.e., k=1,

[0154] (wherein R⁶, R⁷ R⁸, R⁹, R¹⁰, and R¹¹ have the same meanings as inthe general formula (VI), and the condensed ring in the formula mayoptionally contain nitrogen or N-oxide). Further, there can also beexemplified those derivatives having a 1,3-dihyroanthra[2,3-c]thiopheneskeleton and those derivatives having a1,3-dihydronaphthaceno[2,3-c]thiophene skeleton.

[0155] Furthermore, derivatives, in which two adjacent substituentsamong the substituents R⁶, R⁷, R⁸ and R⁹ in the condensedheteropolycyclic compound represented by formula (VI) are combined toeach other through an unsaturated bond to newly form a condensed6-membered ring (ortho-substitution), may also be used and specificexamples thereof include, when k=0, a 1,3-dihydronaphtho[1,2-c]thiophenederivative, when k=1, a 1,3-dihydrophenanthra[2,3-c]thiophene derivativeand a 1,3-dihydrotriphenylo[2,3-c]thiophene derivative, and when k=2, a1,3-dihydrobenzo[a]anthraceno[7,8-c]thiophene derivative.

[0156] The condensed ring in the condensed heteropolycyclic compoundrepresented by formula (VI) may optionally contain nitrogen or N-oxideand examples of such a condensed ring include, when k=0,1,3-dihydrothieno[3,4-b]quinoxaline,1,3-dihydrothieno[3,4-b]quinoxaline-4-oxide and1,3-dihydrothieno[3,4-b]quinoxaline-4,9-dioxide.

[0157] As the substituent group for the substituted phenyl representedby R⁶, R⁷, R⁸, R⁹, R¹⁰, and R¹¹, there can be cited Cl, Br, I, F, orCF₃.

[0158] As stated above, the condensed heteropolycyclic compoundsrepresented by the general formula (VI) have a 1,3-dihydro typecondensed heteropolycyclic compound skeleton as described above, so thatthey can readily give rise to an electrically conducting polymer by theoxidation reaction process according to the present invention describedherein.

[0159] The polymers having the compounds represented by the generalformulae (VI), (X), and (XI) are polymers represented by the generalformulae (III), (IV), and (V), respectively.

[0160] The compounds represented by the general formulae (VI), (IX), and(X) include, for example, the compounds represented by the followingstructural formulae.

[0161] In the solid electrolytic capacitor of the present invention, useof a specified electrically conducting polythiophene composition as asolid electrolyte can increase reflow heat resistance, etc.

[0162] The eletrically conducting polythiophene composition preferablycontains a sulfate ion in the electrically conducting polythiophene andpreferably further contains an other anion having a dopant function.

[0163] As the electrically conducting polythiophene, there can be usedthose represented by the general formula (II) above, that is, the onerepresented by the following formula.

[0164] In the formula, R⁴ and R⁵ each independently represents hydrogenatom, a linear or branched, saturated or unsaturated C1-6 alkyl groupand prefererable substituent group includes methyl, ethyl, propyl,isopropyl, vinyl, or allyl.

[0165] Further, C1-6 alkyl groups represented by R⁴ and R⁵ may bond toeach other at any position to form a substituent for forming at leastone 5-, 6- or 7-membered saturated hydrocarbon ring structure containingthe two oxygen elements shown in the formula (II) above and, forexample, 1,2-ethylene, 1,2-propylene, 1,2-dimethylethylene arepreferred.

[0166] Furthermore, the C1-6 alkyl groups represented by R⁴ and R⁵ maybe combined at any position to each other to form an unsaturatedhydrocarbon ring structure such as substituted vinylene group andsubstituted o-phenylene group, and examples thereof include1,2-vinylene, 1,2-propenylene, 2,3-butylen-2-ene, 1,2-cyclohexylene,methyl-o-phenylene, 1,2-dimethyl-o-phenylene and ethyl-o-phenylene. δ isin the range of 0 to 1.

[0167] The sulfate ion in the above-mentioned electrically conductingpolythiophene composition is preferably derived from a reduced form ofpersulfate such as ammonium persulfate or alkali metal persulfate.

[0168] In the solid electrolytic capacitor of the present invention, atleast a portion of the solid electrolyte layer can be rendered alamellar structure by use of the condensed heteropolycyclic polymerrepresented by the general formulae (III) to (V) and the above-mentionedelectrically conducting polythiophene composition. In this case, it ispreferred to form a space portion at least a portion of interlamellarspace of the lamellar structure. Other lamellar structure is formed onthe outer surface of the valve acting metal but it is preferred that itis also formed inside the pores on the dielectric film, the thicknessper unit layer constituting the lamellar structure is in the range of0.01-5 μm, the total thickness of the solid electrolyte layer formed onthe outer surface of the valve acting metal is in the range of 1-200 μm,preferably 1-100 μm, as described above.

[0169] By so constructing, not only the solid electrolyte is excellentin reflow heat resistance but also there can be obtained a solidelectrolytic capacitor which is excellent in the ability of relaxingthermal stress, adhesion with the electrically conducting paste, theability of repairing the oxide dielectric film.

[0170] Next, the invention on the production method will be explained.

[0171] The solid electrolytic capacitor of the present invention can beproduced by polymerizing each heterocyclic compound corresponding to therepeating unit of the above-mentioned heteropolycyclic polymer as asolid electrolyte on a dielectric film which in turn is formed on asurface of a valve acting metal having pores by the action of anoxidizing agent and using the polymer as a solid electrolyte layer.

[0172] The invention of the production method for the solid electrolyticcapacitor described in (29) above is a method in which the condensedheteropolycyclic compound represented by the general formula (VI) ispolymerized in the same manner as above. This method can give rise tothe condensed heteropolycyclic polymer represented by the generalformula (III).

[0173] The condensed heterpolycyclic compound represented by the generalformula (VI) in which K=0, is a compound represented by the generalformula (X) above and the compound represented by the general formula(VI) in which k=1 is a compound represented by the general formula (XI).Specific compounds of those represented by the general formulae (X) and(XI), including those represented by the formulae (a) to (t) above, arethe same as described above.

[0174] Polymerization of the compounds represented by the generalformula (X) or (XI) can give rise to the condensed heteropolycyclicpolymer represented by the general formulae (IV) and (V), respectively.

[0175] The invention in (32) above is a method in which the condensedheteropolycyclic compound represented by the general formula (VII)

[0176] (wherein the symbols have the same meanings as defined above) ispolymerized in the same manner as described above. By this method, thecondensed heteropolycyclic polymer represented by the general formula(III) can be obtained.

[0177] The condensed heteropolycyclic compound represented by thegeneral formula (VII) where K=0 is a derivative having a1,3-dihydroisothianaphthene-2-oxide (or also called1,3-dihydrobenzo[c]thiophene-2-oxide) skeleton represented by thefollowing formula (XII):

[0178] (wherein R⁶ R⁷ R⁸ and R⁹ are the same as in the general formula(VII), and the condensed ring may optionally contain nitrogen orN-oxide) or a derivative having a1,3-dihydronaphtho[2,3-c]thiophene-2-oxide skeleton represented by thefollowing formula (XIII):

[0179] (wherein the substituent R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ are the sameas in the general formula (VII), and the condensed ring may optionallycontain nitrogen or N-oxide). Other examples include a derivative havinga 1,3-dihydroanthra[2,3-c]thiophene-2-oxide skeleton and a derivativehaving a 1,3-dihydronaphthaceno[2,3-c]thiophene-2-oxide skeleton.

[0180] Furthermore, derivatives, in which two adjacent substituentsamong the substituents R⁶, R⁷, R⁸ and R⁹ in the condensedheteropolycyclic compound represented by formula (VII) are combined toeach other through an unsaturated bond to newly form a condensed6-membered ring (ortho-substitution), may also be used and specificexamples thereof include, when K=0, a1,3-dihydronaphtho[1,2-c]thiophene-2-oxide derivative, when k=1, a1,3-dihydrophenanthra[2,3-c]thiophene-2-oxide derivative and a1,3-dihydrotriphenylo[2,3-c]thiophene-2-oxide derivative, and when k=2,a 1,3-dihydrobenzo[a]anthraceno[7,8-c]thiophene-2-oxide derivative.

[0181] The condensed ring in the condensed heteropolycyclic compoundrepresented by formula (VII) may optionally contain nitrogen or N-oxideand examples of such a condensed ring include, when K=0,1,3-dihydrothieno[3,4-b]quinoxaline-2-oxide,1,3-dihydrothieno[3,4-b]quinoxaline-2,4-dioxide and1,3-dihydrothieno[3,4-b]quinoxaline-2,4,9-trioxide.

[0182] As described in the foregoing, the condensed hetero-polycycliccompound represented by formula (VII) has the above-described1,3-dihydro-2-oxide-type condensed heteropolycyclic compound skeletonand can easily provide an electrically conducting polymer composition bythe oxidation reaction process described in the present invention.

[0183] Specific compounds represented by the general formulae (XII) and(XIII) include the following compounds.

[0184] The polymerization process for the compounds of the generalformulae (VI) and (VII) is characterized by the oxidativedehydrogenation reaction (polymerization reaction) of the condensedheteropolycyclic compound and further in the case of the compounds ofthe general formula (VII) it is characterized in that In addition to thereaction, intramolecular dehydrogenation reaction takes place withinpores of a metal oxide dielectric layer and further that due to such areaction, more activation occurs and accelerates the polymerizationreaction to efficiently provide a polymer having a high electricconductivity, which polymer is perferable for the characteristics of acapacitor, e.g., capacity, tan δ, leakage current, impedance, and reflowheat resistance.

[0185] In other words, according to the production process of a solidelectrolyte (polymer) of the present invention, the dehydrogenativeoxidation reaction (4 electron oxidation) of the condensedheteropolycyclic compound can be effectively achieved on or in thevicinity of the surface of a metal oxide in the presence or absence of asolvent under short-time and simple reaction conditions. Therefore, ascompared with the case using a conventionally known dehydrogenativeoxidation reaction of a pyrrole or a thiophene (in this case, 2 electronoxidation polymerization), industrially useful solid electrolyticcapacitor properties can be provided.

[0186] The effect of accelerating the in-situ chemical polymerization inthe dielectric layer may be considered to come out due to thecomplicated finely porous structure or large specific area of thedielectric or due to the surface free energy of the oxide thin film,although the principle thereof is not yet elucidated.

[0187] With respect to conventionally known examples of the method forproducing a polymer, JP-A-63-118323 and JP-A-2-242816 disclose a methodof oxidatively polymerizing a monomer having a1,3-dihydroisothianphthene structure in the presence of an oxidizingagent. This is, however, an example of a mere polymerization method inthe polymer chemistry and the above-described patent publications arecompletely silent on the chemical reaction process (in-situ chemicalpolymerization process) using the effect on the surface of a metal oxidedescribed in the present invention. Synthetic Metals, Vol. 16, pp.379-380 (1986) discloses. a method of oxidatively polymerizing a monomerhaving a 1,3-dihydroisothianaphthene structure in the presence of oxygenand an oxidizing agent together, but this is also an example of meresynthesis reaction. Furthermore, JP-A-62-118509 and JP-A-62-118511disclose use of an electrochemically polymerized polymer as a solidelectrolyte and thus, these patent publications differ in the productionprocess from the present invention. Moreover, the capacitor propertiesare different from those in the present invention.

[0188] According to the production process for the compounds of thegeneral formulae (VII), 1,3-dihydro-2-oxide type condensedheteropolycyclic compound (monomer) is subjected to an intramoleculardehydration reaction and dehydrogenative 2 electron oxidation reaction(polymerization) which takes place within pores of a metal oxidedielectric layer generate in-situ a polymer having a proper electricconductivity. That is, the process is characterized in that theintramolecular dehydrogenation reaction and dehydrogenative 2 electronoxidation reaction described above can be effectively achieved on or inthe vicinity of the surface of a metal oxide in the presence or absenceof a solvent under short-time and simple reaction conditions. Therefore,as compared with the case using a conventionally known dehydrogenativeoxidation reaction of a pyrrole or a thiophene (in this case, 2 electronoxidation polymerization), industrially useful solid electrolyticcapacitor properties can be provided. The effect of accelerating thein-situ chemical polymerization in the dielectric layer may beconsidered to be attributable to the fact that the dielectric is anoxide so that it induces intramolecular dehydration reaction(dehydration effect as a Lewis acid), and that the dielectric has alarge specific area, which efficiently accelerates the above-describeddehydrogenative 2 electron oxidation reaction by the oxidizing.

[0189] The conventionally known methods for producing a polymer (forexample, J. Org. Chem., Vol. 49, p. 3382 (1984)) include a method ofpolymerizing a monomer having a 1,3-dihydroisothianaphthene-2-oxidestructure in the presence of sulfuric acid, but this is merely anexample of mere synthesis reaction and teaches nothing on the chemicalreaction process (in-situ chemical polymerization process) using theeffect on the surface of a metal oxide described in the presentinvention.

[0190] According to the above-mentioned production method of the presentinvention, capacitors having a higher capacity can be provided. That is,according to the present invention, an oxidizing agent is chargedtogether with the monomer alone or further with another anion having adopant ability and by performing step by step the dehydrogenative 4electron oxidation reaction (polymerization) (in the case of thecompounds of the general formula (VI)) or intramolecular dehydrationreaction and dehydrogenative 2 electron oxidation reaction(polymerization) (in the case of the compounds of the general formula(VII)) directly within a metal oxide foil (for example, an formedaluminum foil), a polymer composition can be effectively filled into andformed within the foil. More specifically, the polymerization of acondensed heteropolycyclic compound proceeds through such a process thatan oxidizing agent is carried and activated on the surface of a metaloxide having a porous structure by the coating according to a solutionprocess or by the sublimation or evaporation according to a vapor phaseprocess and then a condensed heteropolycyclic compound is introducedinto the surf ace of the fine structure, if desired, together with acompound capable of donating another anion having a dopant ability,thereby forming the polymer composition on or in the vicinity of thedielectric. By repeating this process step by step, a solid electrolytecomprising the polymer composition can be effectively filled and formedinside the pores. Due to this, homogeneity in the electric conductingpath within the solid electrolyte layer can be remarkably improved,unnecessary formation of stresses inside the pores can be prevented(prevention of rupture of the dielectric layer) and as a result,excellent capacitor properties including high capacity and low impedancecan be realized.

[0191] Further, according to the production method of the presentinvention, solid electrolytic capacitors having excellent soldering heatresistance (heat stability) can be provided. Conventionally knowncapacitors using a solid electrolyte comprising polypyrrole or the likeundergo large fluctuation in the LCR (inductance, capacitance,resistance) values at a high temperature and a high humidity and haspoor reliability. However, the electrically conducting compositionhaving a chemical formula shown in the present invention has excellentheat stability and exhibits good stability in the doped state.Furthermore, this polymer composition is step by step deposited on thesurface of a dielectric and accordingly, a structure of many polymercomposition thin films being overlapped can be formed. Thus, the polymercan prevent damages of the dielectric film and a capacitor havingexcellent heat stability can be provided.

[0192] The oxidizing agent for use in the production method of thepresent invention may be any oxidizing agent as far as oxidationreaction by dehydrogenative 4 electron oxidation or dehydrogenative 2electron oxidation can be satisfactorily effected and the capacitorperformance can be improved in the use environment for the reactionwithin fine pores. In practice, compounds which are industriallyinexpensive and easy to handle are preferred. Specific examples thereofinclude Fe(III) compounds such as FeCl₃, FeClO₄and Fe (organic acidanion) salt, anhydrous aluminum chloride/cuprous chloride, alkali metalpersulfates, ammonium persulfate salts, peroxides, manganese such aspotassium permanganese, quinones such as2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ),tetrachloro-1,4-benzoquinone and tetracyano-1,4-benzoquinone, halogenssuch as iodine and bromine, peracid, sulfuric acid, fuming sulfuricacid, sulfur trioxide, sulfonic acids such as chlorosulfuric acid,fluorosulfuric acid and amidosulfuric acid, ozone, and combinations of aplurality of these oxidizing agents.

[0193] Examples of the base compound for the organic acid anionconstituting the Fe (organic acid anion) salt include an organosulfonicacid, an organocarboxylic acid, an organophosphoric acid and anorganoboric acid. Specific examples of the orgnosulfonic acid includebenzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid,ethanesulfonic acid, α-sulfonaphthalene, β-sulfonaphthalene,naphthalenedisulfonic acid, alkylnaphthalenesulfonic acid (examples ofthe alkyl group include butyl, triisopropyl and di-t-butyl, etc.).

[0194] Specific examples of the organocarboxylic acid include aceticacid, propionic acid, benzoic acid and oxalic acid. Furthermore, in thepresent invention, a polyelectrolyte anion such as polyacrylic acid,polymethacrylic acid, polystyrenesulfonic acid, polyvinylsulfonic acid,polyvinylsulfuric acid, poly-α-methylsulfonic acid, polyethylenesulfonicacid and polyphosphoric acid may also be used. However, these aredescribed only for the purpose of illustrating examples of theorganosulfonic acid and the organocarboxylic acid and the presentinvention is by no means limited thereto. The counter cation of theabove-described anion is not particularly limited in the presentinvention and examples thereof include H⁺, alkali metal ion such as Na⁺and K⁺, and ammonium ion substituted by a hydrogen atom, a tetramethylgroup, a tetraethyl group, a tetrabutyl group or a tetraphenyl group. Ofthese oxidizing agents, oxidizing agents containing a trivalent Fecompound, cuprous chloride, a persulfuric acid alkali salt, an ammoniumpersulfate, a manganic acid or a quinone are suitably used.

[0195] Examples of the anion having a dopant ability which is allowed tobe present together, if desired, in the production process of thepolymer composition of the present invention include electrolyticcompounds comprised of anion of oxidizing agent (a reduced form of theoxidizing agent) produced from the above-described oxidizing agent as acounter anion, and other anionic electrolytes. Specific examples thereofinclude Group 5B element halide anions such as PF₆ ⁻, SbF₆ ⁻ and AsF₆ ⁻,Group 3B element halide anions such as BF₄ ⁻, halogen anions such as,I⁻(I₃ ⁻), Br⁻ and Cl⁻, halogen acid anions such as ClO₄ ⁻, Lewis acidanions such as AlCl₄ ⁻, FeCl₄ ⁻ and SnCl₅ ⁻, and protonic acid anionsincluding inorganic acid anions such as NO₃ ⁻ and SO₄ ²⁻, organosulfonicacid anions such as p-toluenesulfonic acid, naphthalenesulfonic acid,C1-5 alkyl-substituted naphthalene sulfonic acid, CF₃SO₃ ⁻ and CH₃SO₃ ⁻,and carboxylic acid anion such as CH₃COO⁻ and C₆H₅COO⁻. Other examplesinclude polyelectrolytic anions of the compounds such as polyacrylicacid, polymethacrylic acid, polystyrenesulfonic acid, polyvinylsulfonicacid, polyvinylsulfuric acid, poly-α-methylsulfonic acid,polyethylenesulfonic acid and polyphosphoric acid. However, the presentinvention is by no means limited thereto. Of these, preferred are anionsof a high molecular or low molecular organosulfonic acid compound and apolyphosphoric acid, and more preferred is an anion of an aromaticsulfonic acid compound such as sodium dodecylbenzylsulfonate and sodiumnaphthalenesulfonate.

[0196] The reaction solvent for use in the production method of thepresent invention may be any solvent as far as it can dissolve themonomer, the oxidizing agent and the electrolyte having a dopant abilityindividually or altogether. Examples thereof include ethers such astetrahydrofuran (THF), dioxane and diethyl ether, aprotic polar solventssuch as dimethylformamide (DMF), acetonitrile, benzonitrile,N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO), esters such asethyl acetate and butyl acetate, nonaromatic chlorine solvents such aschloroform and methylene chloride, nitro compounds such as nitromethane,nitroethane and nitrobenzene, alcohols such as methanol, ethanol andpropanol, organic acids such as formic acid, acetic acid and propionicacid, acid anhydrides of the organic acid (e.g., acetic anhydride),water, and a mixed solvent thereof. The compound may be introduced intothe dielectric layer (may be subjected to polymerization) in a solventsystem, namely, a two-liquid system or a three-liquid system, where theabove-described oxidizing agent and/or the electrolyte having a dopantability and the monomer are individually dissolved.

[0197] The production method of the present invention described in (35)above is a method in which in a heterocyclic compound represented by thefollowing general formula (VIII)

[0198] (wherein R¹, R², and X have the same meanings as defined above)is polymerized a thiophene monomer represented by the following generalformula (IX)

[0199] (wherein R⁴ and R⁵ have the same meanings as defined above) bythe action of a persulfate (oxidizing agent) in the presence of anapthalenesulfonate anion.

[0200] This method provides an electrolyte layer comprising anelectrically conducting polythiophene composition containing a sulfateion and a naphthalenesulfonate anion. The polythiophene in thecomposition is that represented by the general formula (II) above.

[0201] Preferred substituents in the general formula (IX) are the sameas described in the explanation on the electrically conductingpolythiophene represented by the general formula (II).

[0202] Out of thiophenes represented by formula (IX) for use in theproduction method of the present invention, a part of monomer compoundsincluding 3,4-dioxyethylene-thiophene are already known (JP-A-2-15611(U.S. Pat. No. 4,910,645)). Furthermore, out of the persulfates as theoxidizing agent for use in the present invention, use of ammoniumpersulfate (hereinafter simply referred to as “APS”) or alkali metalpersulfate is also known.

[0203] However, in the present invention, the electrically conductingcomposition after oxidative polymerization has a sulfate ion content offrom 0.1 to 10 mol %, preferably from 0.2 to 5 mol %, and anaphthalenesulfonate ion content of from 1 to 50 mol %, preferably from5 to 40 mol %.

[0204] A solid electrolytic capacitor comprising a solid electrolyteformed of an polymer containing a structural unit represented by thegeneral formula (IX) in the electrically conducting composition hasparticularly excellent voltage withstanding property and this hashitherto been not known. In the present invention, the total of thesulfate ion content and the naphthalenesulfonate ion content ispreferably from 1.1 to 60 mol % based on the entire weight of theelectrically conducting composition. According to the processesdescribed above, conditions for production can be determined so that thesulfate ion contents and so on in the composition may fall within theabove range.

[0205] In the production of a capacitor, the method for forming theabove-described solid electrolyte plays an important role in theproduction of a capacitor for attaining high capacity and high frequencyproperty and improving tan δ, leakage current, heat resistance (reflowproperty) and durability. More specifically, it is important to form adensely filled solid electrolyte and thereby improve the homogeneity ofthe electric conducting path. To this effect, the constitution of theelectrically conducting composition has a great effect on the capacityproperties. In the present invention, the process ofoxidation-polymerizing the above-described thiophene monomer by theaction of a persulfate in the coexistence of a naphthalenesulfonateanion to produce the solid electrolyte is performed in a plurality ofrepetitions, preferably from 5 to 20 repetitions to an anode substrate(valve acting metal) and thereby an objective solid electrolyte can beeasily obtained. In this process, a step where the dielectric layer iscoated with or dipped in a solution containing the above-describedthiophene monomer and naphthalenesulfonate anion (Solution 1) may beprovided separately before or after a step where the layer is coatedwith or dipped in a solution having dissolved therein a persulfate(Solution 2). Solution 1 and Solution 2 may use the same solvent or maydiffer in the solvent system.

[0206] Repeating the oxidation-polymerization process facilitates theproduction of a solid electrolyte having excellent soldering heatresistance (heat stability). The capacitor comprising a solidelectrolyte formed of an electrically conducting composition of thepresent invention has excellent heat stability and exhibits goodstability in the doped state, because the polymer composition havingsuch a sulfate ion and a naphthalenesulfate ion as described above canbe filled well step by step into the dielectric surface, even inside thepore, and thereby a structure where many thin films of the polymercomposition are overlaid one on another can be formed. As a result, thepolymer can prevent damages of the dielectric film and a capacitorhaving excellent heat stability can be provided.

[0207] The persulfate used in the production method is preferablyammonium persulfate or potassium persulfate.

[0208] The reaction solvent used is the same as those used in thereaction of the compounds represented by the general formulae (VI) and(VII).

[0209] Preferred conditions for the polymerization reaction using thecompounds represented by the general formulae (VI), (VII), or (IX) aredescribed below.

[0210] The concentration of the monomer represented by formulae (VII),(VI), or (IX) for use in the production method of a capacitor of thepresent invention varies depending on the substituent (species) of thecompound or the kind of solvent, however, it is in general preferablyfrom 10⁻³ to 10 mol/l, more preferably from 10⁻² to 5 mol/l. Thereaction temperature is selected according to respective reactionprocesses and cannot be specifically limited, however, it is generallyfrom −70 to 250° C., preferably from 0 to 150° C. and more preferablyfrom 15 to 100° C.

[0211] In the above-mentioned polymerization method, it is preferredthat first the oxidant is carried on the surface of the dielectric layerand then the monomer is supplied to carry out the polymerization.

[0212] The solid electric conductor thus produced has an electricconductivity of from 0.1 to 200 S/cm, preferably from 1 to 100 S/cm,more preferably from 10 to 100 S/cm.

[0213] Generally, capacitors are jacketed with a an electric conductorlayer on the solid electrolyte layer (semiconductor) in order to improveelectrical contact. In the case of the capacitor of the presentinvention, it is preferred that such an electric conductor layer isprovided, for example, by solidifying or plating an electricallyconducting paste, vapor deposition of a metal or forming an electricallyconducting resin film.

[0214] Next, explanation will be made on a high performance solidelectrolytic capacitor which is small in size and has a low impedanceand a durability to sparking voltage test, with its capacitor containingsulfoquinone having at least one sulfo anion group and a quinonestructure in the molecule and in addition to the quinone an other anionhaving a dopant ability, and a production method therefor, which arepreferred embodiments of the present invention as described in (15) to(21) and (38) to (56) above.

[0215] In the present invention, by incorporating into the electricallyconducting polymer composition a sulfoquinone anion having one or moresulfoanion groups and a quinone structure in the molecule (hereinaftersimply referred to as a “sulfoquinone”) as a main anion having a dopantability and further containing an anion other than a sulfoquinone as anauxiliary dopant, a preferred electrically conducting composition layer(charge-transfer complex) having heat resistance can be formed. As aresult, a solid electrolytic capacitor having excellent low impedanceproperty and a production method thereof can be provided.

[0216] The π electron-conjugated polymer in an electrically conductingpolymer composition suitable for the capacitor of the present inventionis a polymer having a π electron-conjugated structure in,the polymermain chain structure. Specific examples thereof include polyaniline,poly-p-phenylene, poly-p-phenylenevinylene, polythienylenevinylene,polyheterocyclic polymer and substituted derivatives thereof. Of thesespecific examples, preferred is a π electron-conjugated polymercomprising a structural unit represented by formula (I):

[0217] (wherein the symbols have the same meanings as defined above.)and more preferred is a π electron-conjugated polymer comprising astructural unit represented by formula (II).

[0218] (wherein the symbols have the same meanings as defined above.)

[0219] The polymer represented by the general formula (I) above can beobtained by polymerizing a heterocyclic compound represented by thegeneral formula (VIII)

[0220] (wherein R¹, R² and X have the same meanings as defined above),and the polymer represented by the general formula (II) above can beobtained by polymerizing a compound represented by the general formula(IX)

[0221] (wherein R⁴ and R⁵ have the same meanings as defined above).

[0222] In formulae (I) and (VIII), useful examples of the linear orbranched, saturated or unsaturated C1-6 alkyl group represented by thesubstituent R¹, R²or R³ include methyl, ethyl, vinyl, propyl, allyl,isopropyl, butyl and 1-butenyl. Useful examples of the linear orbranched, saturated or unsaturated C1-6 alkoxy group include methoxy,ethoxy, propoxy, isopropoxy and butoxy. Useful examples of thesubstituent other than the above-described alkyl group or alkoxy groupinclude a nitro group, a cyano group, a phenyl group and a substitutedphenyl group (e.g., phenyl group substituted by a halogen group such asCl, Br, F, etc.). The alkyl group or alkoxy group in R¹ or R²mayoptionally contain in the chain thereof a carbonyl bond, an ether bond,an ester bond, an amide bond or an imino bond, and particularly usefulexamples thereof include methoxyethoxy and methoxyethoxyethoxy.

[0223] The substituents R¹ and R² may be combined to each other at anyposition to form at least one divalent chain for forming at least one5⁻, 6- or 7-membered saturated or unsaturated ring structure. Examplesof the substitution in formula (I) or (VIII) include a3,4-propylene-substituted structure, a 3,4-butylene-substitutedstructure, 3,4-butenylene-substituted structure,3,4-butadienylene-substituted structure and a naphtho[2,3-c]-condensedstructure.

[0224] X represents a hetero atom and examples thereof include S, O, Se,Te and NR³ The above-described 3,4-butadienylene-substituted structurewhere X is S is denoted an isothianaphthenylene structure in the case ofthe monomer compound structure of formula (I) or denotedisothianaphthene in the case of the monomer compound structure offormula (VIII). Similarly, the naptho[2,3-c]condensed structure isdenoted a naphtho[2,3-c]thienylene structure in the case of formula (I)or denoted naphtho[2,3-c]thiophene in the case of the monomer compoundstructure of formula (VIII). In the formulae, δ represents a number ofcharges per the repeating structure unit, of from 0 to 1.

[0225] Useful examples of the substituents R⁴and R⁵ in formulae (II) and(IX) include methyl, ethyl, propyl, isopropyl, vinyl and allyl.Furthermore, R⁴and R⁵may be substituents of which C¹-6 alkyl groups arebonded to each other at any position to form at least one or more 5-, 6-or 7-membered heterocyclic ring structure containing the two oxygenelements in formula (II) or (IX). Preferred examples thereof include1,2-ethylene, 1,2-propylene and 1,2-dimethylethylene. Furthermore, theC1-6 alkyl groups of R⁴ and R⁵ may be combined to each other at anyposition to form an unsaturated hydrocarbon ring structure such assubstituted vinylene group and substituted o-phenylene group, andexamples thereof include 1,2-vinylene, 1,2-propenylene,2,3-butylen-2-ene, 1,2-cyclohexylene, methyl-o-phenylene,1,2-dimethyl-o-phenylene and ethyl-o-phenylene.

[0226] Among the monomer compounds represented by formula (VIII) for usein the solid capacitor and the production process thereof of the presentinvention, for example thiophene (R¹═R²═H, X═S) and pyrrole (R¹═R²═H,X═NH), or among thiophenes represented by formula (IX), a monomercompound of 3,4-dioxyethylene-thiophene are known. Also, many ofoxidizing agents which can polymerize such a monomer compound are known.However, a capacitor comprising a solid electrolyte formed of anelectrically conducting composition containing a sulfoquinone anion as adopant and using another anion in combination as an auxiliary dopant hasheretofore been unknown.

[0227] More specifically, the capacitor disclosed in JP-A-10-32145(European Patent Application Laid-open No. 820076(A2)) uses anelectrically conducting composition which is apoly(3,4-dioxyethylene-thiophene) having doped therein a specificorganic sulfonic acid such as benzoquinonesulfonic acid or alicyclicsulfonic acid, thus, the dopant is only the organic sulfonate anionhaving a specific chemical structure. This patent publication disclosesa technique of providing an organic sulfonate anion from an iron(III)compound used in the oxidizing agent or an anion constituting a cupriccompound but addition of an auxiliary dopant is not disclosed therein.

[0228] The solid electrolytic capacitor of the present inventioncomprises a solid electrolyte constituted by anions such that theabove-described sulfoquinone anion is contained in an amount of from 0.1to 50 mol % and another anion in addition to the above-described anionis contained in an amount of from 0.1 to 10 mol %, based on the totalweight of the π-conjugated polymer composition, and is particularlycharacterized by having excellent low impedance property with otherproblems described above to be solved. Such a capacitor has beenheretofore not known. Furthermore, although JP-B-6-101418 (U.S. Pat. No.4,959,753) discloses an example of the solid electrolytic capacitorcontaining as a dopant an anthraquinonesulfonate anion which is one ofthe sulfoquinone anion, this capacitor has a constitution such that anelectrically conducting polymer composition is provided on a valve metalhaving provided thereon a dielectric film on which manganese dioxide isattached. Thus, the constitution differs from that of the presentinvention. Moreover, this constitution is disadvantageous in that, asdescribed above, the oxide film layer may be ruptured at the time offormation (thermal decomposition) of the manganese dioxide.

[0229] The capacitor of the present invention comprises a solidelectrolyte capable of providing a capacitor excellent particularly inthe low impedance property, wherein the sulfoquinone content ispreferably from 1 to 30 mol % based on the total weight of theπ-conjugated polymer composition. On the other hand, in the solidelectrolyte of the present invention, the content of another anion inaddition to a sulfoquinone anion is preferably from 0.1 to 5 mol % basedon the total weight of the polymer composition. In the production methodof the present invention, an oxidizing agent is used at thepolymerization of a monomer compound, the another anion is contained asa reduced form of anion of the oxidizing agent, although it may be addedby a different method and the method is not limited.

[0230] Usually, the method for producing the above-described solidelectrolyte plays an important role in the production of a capacitor forattaining high-capacity and high frequency property and improving tan δ,leakage current, heat resistance (reflow property), impedance,durability, etc. To these effects, it is important to properly combinethe π electron conjugated structure constituting a solid electrolyte andthe dopant, and to densely fill and form an electrically conductingpolymer composition layer on a fine dielectric layer to thereby increaseor improve the homogeneity of the electric conducting path. Inparticular, the constitution of the electrically conducting polymercomposition has a great effect on the capacity properties.

[0231] The production method of the present invention is characterizedby allowing a sulfoquinone anion and another anion to be presenttogether as dopants for the polymer of the above-described monomercompound. More specifically, the production method of the presentinvention comprises a step of producing a polymer composition as thesolid electrolyte on the dielectric surface and the polymer compositionis produced by causing oxidative polymerization of a monomer compoundrepresented by formula (VIII) or preferably by formula (IX) on thefinely porous dielectric layer in the presence of a compound capable ofproviding a sulfoquinone anion by the action of the oxidizing agent. Byrepeating this production process once or more, preferably from 3 to 20times per one anode substrate, a dense solid electrolyte layer can beeasily formed.

[0232] For example, in one preferred embodiment of the productionprocess, the polymerization step may include a step of dipping avalve-acting metal anode foil having formed thereon an oxide dielectricfilm layer in a solution containing an oxidizing agent (Solution 1) anda step of dipping the anode foil in a solution containing a monomercompound and a sulfoquinone anion (Solution 2), or may include a step ofdipping the anode foil in Solution 2 and then dipping it in Solution 1or a step of dipping the anode foil in Solution 1 and then dipping it inSolution 2.

[0233] In another embodiment, the production step may include a step ofdipping the anode foil in a solution containing an oxidizing agent and asulfoquinone anion (Solution 3) and a step of dipping the anode foil ina solution containing a monomer compound (Solution 4) or may include astep of dipping the anode foil in Solution 4 and then dipping it inSolution 3 or a step of dipping the anode foil in Solution 3 and thendipping it in Solution 4. Solution 1 to 4 each may be used in the formof a suspension.

[0234] Furthermore, the dipping process may be replaced to the coatingoperation. Solutions 1 to 4 may be the same, if desired, or may bedifferent solvent systems. According to the kind of the solvent, adrying step may be additionally provided between the process of Solution1 and Solution 2 or between the process of Solution 3 and Solution 4.After producing the solid electrolyte, a step of washing the device withan organic solvent or with water may be provided. In this case, it issimple and preferred to use the solvent used in any of Solutions 1 to 4as the organic solvent for use in the washing, however, any solvent maybe used as, far as it can merely dissolve the monomer compound, thesulfoquinone compound or the compound providing another anion having adopant ability.

[0235] The above-described repetition of oxidation polymerizationprocess facilitates the production of a solid electrolyte havingexcellent soldering heat resistance (heat stability). In conventionallyknown capacitors using a solid electrolyte comprising polypyrrole or thelike, the capacitor properties greatly fluctuate at a high temperatureand a high humidity and the reliability is low. However, the capacitorcomprising a solid electrolyte formed with an electrically conductingcomposition of the present invention has excellent heat stability andexhibits good stability in the doped state, because the polymercomposition having the above-described two or more dopants can be filledwell step by step into the dielectric surface and even inside the pore,and thereby a structure where many thin films of the polymer compositionare overlaid one on another can be formed. As a result, a capacitorhaving excellent heat stability such that the dielectric film isprevented from damages by the polymer can be provided.

[0236] The sulfoquinone anion used in the present invention is acompound anion having a chemical structure such that ketone groups in aquinone structure and a sulfonic acid group as an electron withdrawinggroup are bound as the substituents within the same molecule.Accordingly, this anion differs from conventionally known molecularanions (e.g., ClO₄ ⁻, BF₄ ⁻, Cl⁻, SO₄ ²⁻, etc.) in the dopant ability(e.g., stability of the charge transfer complex, electric conductivity)and the chemical properties, and further exhibits superior effects ascompared with the system of using a conventionally known molecular anion(e.g., ClO₄ ⁻, BF₄ ⁻, Cl⁻, SO₄ ²⁻, etc.) alone. More specifically, whena plurality of capacitor devices are manufactured and compared,particularly excellent effects can be brought out on the capacitorperformance.

[0237] The sulfoquinone used in the present invention is a generic termof compounds having one or more sulfonic acid groups and a quinonestructure within the molecule and any may be used as far as it has achemical structure of allowing effective working as a dopant in the formof the sulfonate anion. Examples of the sulfoquinone basic skeletoninclude p-benzoquinone, o-benzoquinone, 1,2-naphthoquinone,1,4-naphthoquinone, 2,6-naphthoquinone, 9,10-anthraquinone (hereinaftersimply referred to as an “anthraquinone”), 1,4-anthraquinone,1,2-anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone,6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone,camphorquinone, 2,3-bornanedione, 9,10-phenanthrenequinone and2,7-pyrenequinone

[0238] Furthermore, the sulfonic acid group in the above-describedsulfoquinone includes an aromatic sulfonic acid structure resulting fromreplacing one or more hydrogens of the quinone compound by a sulfonicacid group, or an aliphatic sulfonic acid structure resulting fromreplacement by sulfoalkylene group through a divalent saturated orunsaturated C1-12 hydrocarbon group. Also, a chemical structureresulting from replacing one or more hydrogens of the sulfoquinone by asaturated or unsaturated C1-12, preferably C1-6, alkyl or alkoxy group,or by a substituent selected from F, Cl and Br may also be used.

[0239] In particular, the sulfoquinone for use in the present inventionis preferably a sulfoquinone having a skeleton of anthraquinone,1,4-naphthoquinone or 2,6-naphthoquinone. Examples of anthraquinoneswhich can be used include anthraquinone-1-sulfonic acid,anthraquinone-2-sulfonic acid, anthraquinone-1,5-disulfonic acid,anthraquinone-1,4-disulfonic acid, anthraquinone-1,3-disulfonic acid,anthraquinone-1,6-disulfonic acid, anthraquinone-1,7-disulfonic acid,anthraquinone-1,8-disulfonic acid, anthraquinone-2,6-disulfonic acid,anthraquinone-2,3-disulfonic acid, anthraquinone-2,7-disulfonic acid,anthraquinone-1,4,5-trisulfonic acid,anthraquinone-2,3,6,7-tetrasulfonic acid, and/or an alkali metal saltand/or ammonium salt thereof.

[0240] Examples of 1,4-naphthoquinones which can be used include1,4-naphthoquinone-5-sulfonic acid, 1,4-naphthoquinone-6-sulfonic acid,1,4-naphthoquinone-5,7-disulfonic acid,1,4-naphthoquinone-5,8-disulfonic acid, and/or an alkali metal and/orammonium salt thereof.

[0241] Examples of 2,6-naphthoquinones which can be used include2,6-naphthoquinone-1-sulfonic acid, 2,6-naphthoquinone-3-sulfonic acid,2,6-naphthoquinone-4-sulfonic acid, 2,6-naphthoquinone-3,7-disulfonicacid, 2,6-naphthoquinone-4,8-disulfonic acid, and/or an alkali metaland/or ammonium salt thereof.

[0242] The sulfoquinone further may be selected from industrial dyes andexamples thereof include Anthraquinone Iris R and Anthraquinone VioletRN-3RN. These industrial dyes each may also be used as a usefulsulfoquinone-based dopant in the form of the above-described salt.

[0243] The sulfoquinone for use in the present invention participatesinto the polymerization reaction of the monomer compound depending onthe compound and acts as one oxidative dehydrogenating agent. A protonadduct of the quinone structure, namely a hydroquinone structure, orquinhydron resulting from the reduction of the sulfoquinone in thepolymerization reaction may be contained as it is as a dopant in thesolid electrolyte.

[0244] The oxidizing agent for use in the present invention may be anyoxidizing agent suitable for the oxidation polymerization of pyrrole orthiophenes. Examples of the oxidizing agent which can be used includeoxidizing agents over a wide range, such as iron(III) chloride,Fe(ClO₄)₃ organic acid iron(III), inorganic acid iron(III),alkylpersulfate, ammonium persulfate, hydrogen peroxide and K₂Cr₂O₇described in JP-A-2-15611 (U.S. Pat. No.4,910,645). Examples of theorganic acid of organic acid iron(III) include a similar alkylsulfonicacid such as methanesulfonic acid and dodecylbenzenesulfonic acid, and aC1-20 aliphatic carboxylic acid. However, the oxidizing agent may berestricted in the range of use by the chemical structure of the monomercompound represented by formula (III), the oxidizing agent, reactionconditions and the like. For example, according to Handbook ofConducting polymers, page 99, Marcel Dekker, Inc. (1987), FIG. 5, thespecies of the substituent greatly affects the oxidation potential (oneindex for showing whether the polymerization readily or difficultlyoccurs) and in turn, governs the oxidation (polymerization) ofthiophenes (oxidation potential expands over a wide range of from about1.8 to about 2.7 V). Accordingly, in practice, the combination of themonomer compound and oxidizing agent used and the reaction conditions isimportant.

[0245] The anion other than the sulfoquinone anion is a reductant anionafter the reaction of the oxidizing agent and specific examples thereofinclude chloride ion, ClO₄ ⁻, aliphatic organic carboxylate anion havingfrom 1 to 12 carbon atoms, sulfate ion, phosphate anion, aliphaticorganophosphate anion having from 1 to 12 carbon atoms and borate anion.Furthermore, an electron acceptor dopant such as NO⁺ and NO₂ ⁺ salt(e.g., NOBF₄, NOPF₆, NOSbF₆, NOAsF₆, NOCH₃SO₃, NO₂BF₄, NO₂PF₆,NO₂CF₃SO₃) may also be used.

[0246] In the production method of a solid electrolytic capacitor of thepresent invention, the chemical polymerization of a thiophenerepresented by formula (IX) is particularly preferably performed using apersulfate. The use of iron(III) salt-based oxidizing agent has aproblem in that an iron element remains and adversely affects thecapacitor properties. Persulfates suitable for the monomer compoundrepresented by formula (IX) are not suitable for the thiophenerepresented by formula (VIII) (R¹═R²═H, X═S) and thus, the use of theoxidizing agent has a restriction. Examples of the persulfate which canbe particularly suitably used for the chemical polymerization of athiophene represented by formula (IX) include ammonium persulfate andpotassium persulfate.

[0247] Preferred conditions for the producing (polymerization) reactionare described below.

[0248] The concentration of the monomer compound represented by formula(VIII) or preferably by formula (IX) for use in the production method ofa capacitor of the present invention and the concentrations of theoxidizing agent and the sulfoquinone used vary depending on the kind ofthe compound or substituents thereof and the combination with a solventor the like. However, it is in general from 1×10⁻⁴ to 10 mol/l,preferably from 1×10⁻³ to 5 mol/l. The reaction temperature is selectedaccording to respective reaction processes and cannot be specificallylimited, however, it is generally from −70 to 250° C., preferably from 0to 150° C. and more preferably from 15 to 100° C.

[0249] Examples of the solution for use in the production method of thepresent invention or the solvent for use in washing after thepolymerization include ethers such as tetrahydrofuran (THF), dioxane anddiethyl ether, ketones such as acetone and methyl ethyl ketone, aproticpolar solvents such as dimethylformamide (DMF), acetonitrile,benzonitrile, N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO),esters such as ethyl acetate and butyl acetate, nonaromaticchlorine-type solvents such as chloroform and methylene chloride, nitrocompounds such as nitromethane, nitroethane and nitrobenzene, alcoholssuch as methanol, ethanol and propanol, organic acids such as formicacid, acetic acid and propionic acid, acid anhydrides of the organicacid (e.g., acetic anhydride), water, and a mixed solvent thereof. Ofthese, preferred are water, an alcohol, a ketone and/or a combinationthereof.

[0250] The solid electrolyte thus produced has an electric conductivityof from 0.1 to 200 S/cm, preferably from 1 to 100 S/cm, more preferablyfrom 10 to 100 S/cm.

[0251] In the present invention, for one part electrode, a knownmaterial such as a foil or bar having a valve action of aluminum,titanium, tantalum, niobium or an alloy using such a material as asubstrate, or a sintered body mainly comprising such a material. Thismetal electrode is used after treating the surface thereof by a knownmethod such as etching or chemical forming so as to increase thespecific surface area, and thereby forming a metal oxide film layer onthe metal foil.

[0252] The solid electrolyte is preferably formed by effecting theproducing process on the dielectric layer. In particular, a method ofchemically depositing an organic electric conductor having excellentheat resistance of the present invention on a dielectric material havinga porous or void structure is preferred. Furthermore, in order to attaingood electrical contacting, an electric conductor layer is preferablyprovided on the semiconductor and the electric conductor layer isformed, for example, by solidifying or plating an electricallyconducting paste, vapor deposition of a metal or forming an electricallyconducting resin film.

[0253] Next, explanation will be made on a high performance solidelectrolytic capacitor which is small in size and has a low impedanceand a durability to sparking voltage test, with its capacitor containinganthracenesulfonic acid selected from at least oneanthracenemonosulfonic acid having one sulfonate group or itsderivatives as a dopant, and a production method therefor, which arepreferred embodiments of the present invention as described in (22) to(28) and (57) to (75) above.

[0254] In the present invention, by incorporating into the electricallyconducting polymer composition at least one anthracenemonosulfonic acidselected from anthracenesulfonic acid having one sulfonate group or itsderivatives (hereinafter simply referred to as a “anthracenemonosulfonicacid”) anion as a main anion having a dopant ability, a preferredelectrically conducting composition layer (charge-transfer complex)having heat resistance can be formed. As a result, a solid electrolyticcapacitor having excellent low impedance property and a productionmethod thereof can be provided. In addition to theanthracenemonosulfonate anion dopant, a further anion may be added as adopant.

[0255] The π electron-conjugated polymer in an electrically conductingpolymer composition suitable for the capacitor of the present inventionis a polymer having a π electron-conjugated structure in the polymermain chain structure. Specific examples thereof include polyaniline,poly-p-phenylene, poly-p-phenylenevinylene, polythienylenevinylene,polyheterocyclic polymer and substituted derivatives thereof. Of thesespecific examples, preferred is a π electron-conjugated polymercomprising a structural unit represented by the general formula (I)above, and more preferred is a π electron-conjugated polymer comprisinga structural unit represented by the general formula (II) above.

[0256] The general formulae (I) and (VIII) above contain theabove-mentioned sulfoquinone having a sulfo anion group and a quinonestructure in the molecule and as the dopant other than quinone, the sameexplanation as the solid electrolytic capacitor containing other anionhaving a dopant ability is also applicable so that detailed descriptionwill be omitted here.

[0257] Among the monomer compounds represented by formula (VIII) for usein the solid electrolytic capacitor and the production process thereofof the present invention, for example thiophene (R¹═R²═H, X═S) andpyrrole (R¹═R²═H, X═NH), or among thiophenes represented by formula(IX), a monomer compound of 3,4-dioxyethylene-thiophene are known. Also,many of oxidizing agents which can polymerize such a monomer compoundare known. However, a capacitor comprising a solid electrolyte formed ofan electrically conducting composition containing aanthracenemonosulfonate (meaning a species of anion, herein) having asulfo group as a dopant and using another anion in combination as anauxiliary dopant has heretofore been unknown.

[0258] More specifically, the capacitor disclosed in JP-A-10-32145(European Patent, Application Laid-open No. 820076(A2)) discloses apolymer of a monomer selected from pyrrole, thiophene, furan, anilineand derivatives thereof doped with an aromatic polysulfonic acidcompound having a plurality of sulfo groups in the molecule as a dopant,but the above-mentioned anthracenemonosulfonic acid having a sulfo groupused in the capacitor of the present invention has been unknown. Furthercombined use together with other dopant other thananthracenemonosulfonate has also been unknown.

[0259] The preferred embodiment of the solid electrolytic capacitor ofthe present invention comprises a solid electrolyte which comprisesdopants such that the above-described anthracenemonosulfonate iscontained in an amount of from 0.1 to 50 mol % and another anion inaddition to the above-described anion is contained in an amount of from0.1 to 10 mol %, based on the total weight of the π-conjugated polymercomposition, and is particularly characterized by having excellent lowimpedance property with other problems described above to be solved.Such a capacitor has been heretofore not known.

[0260] In the capacitor of the present invention, the content of theabove-mentioned anthracenemonosulfonate is preferably in the range of1-30 mol % based on the total weight of the π electron-conjugatedpolymer composition for providing a capacitor having particularlyexcellent low impedance property. On the other hand, the content ofother dopant other than the anthracenemonosulfonate is in the range of0.1 to 5 mol % based on the total weight of the repeating units of the πelectron-conjugated polymer. The other dopant is used as a reducedchemical species (anion) of an oxidizing agent since the oxidizing agentis used in the polymerization of monomer compounds in the productionmethod of the present invention. It may be added in a different mannerand the method of co-existence is not limited particularly.

[0261] Usually, the method for producing (formation of) theabove-described solid electrolyte plays an important role in theproduction of a capacitor for attaining high capacity and high frequencyproperty and improving tan δ, leakage current, heat resistance (reflowproperty), impedance, durability, etc. To these effects, it is importantto properly combine the a electron conjugated structure constituting asolid electrolyte and the dopant, and to densely fill and form anelectrically conducting polymer composition layer on a fine dielectriclayer to thereby increase or improve the homogeneity of the electricconducting path. In particular, the constitution of the electricallyconducting polymer composition has a great effect on the capacityproperties.

[0262] The production method of the present invention is characterizedby allowing an anthracenemonosulfonate and another anion to be presenttogether as dopants for the polymer of the above-described monomercompound. More specifically, the production method of the presentinvention comprises a step of producing a polymer composition as thesolid electrolyte on the dielectric surface and the polymer compositionis produced by causing oxidative polymerization of a monomer compoundrepresented by formula (VIII) or preferably by formula (IX) on thefinely porous dielectric layer in the presence of a compound capable ofproviding an anthracenemonosulfonate by the action of the oxidizingagent. By repeating this production process once or more, preferablyfrom 3 to 20 times per one anode substrate, a dense solid electrolytelayer can be easily formed.

[0263] For example, in one preferred embodiment of the productionprocess, the polymerization step may include a step of dipping avalve-acting metal anode foil having formed thereon an oxide dielectricfilm layer in a solution containing an oxidizing agent (Solution 1) anda step of dipping the anode foil in a solution containing a monomercompound and an anthracenemonosulfonate (Solution 2), or may include astep of dipping the anode foil in Solution 2 and then dipping it inSolution 1 or a step of dipping the anode foil in Solution 1 and thendipping it in Solution 2.

[0264] In another embodiment, the production step may include a step ofdipping the anode foil in a solution containing an oxidizing agent andan anthracenemonosulfonate (Solution 3) and a step of dipping the anodefoil in a solution containing a monomer compound (Solution 4) or mayinclude a step of dipping the anode foil in Solution 4 and then dippingit in Solution 3 or a step of dipping the anode foil in Solution 3 andthen dipping it in Solution 4. Solution 1 to 4 each may be used in theform of a suspension.

[0265] Furthermore, the dipping process may be replaced to the coatingoperation. Solutions 1 to 4 may be the same, if desired, or may bedifferent solvent systems. According to the kind of the solvent, adrying step may be additionally provided between the process of Solution1 and Solution 2 or between the process of Solution 3 and Solution 4.After producing the solid electrolyte, a step of washing the device withan organic solvent or with water may be provided. In this case, it issimple and preferred to use the solvent used in any of Solutions 1 to 4as the organic solvent for use in the washing. However, any solvent maybe used as far as it can merely dissolve the monomer compound, theanthracenemonosulfonic acid compound or the compound providing anotheranion having a dopant ability. The washing step with a solvent candecrease the content of dopants other than anthracenemonosulfonatedopant in the polymer. However, existence of the anthracenemonosulfonatedopant may sometimes contribute to the property of the solidelectrolytic capacitor of the present invention.

[0266] The above-described repetition of oxidation polymerizationprocess facilitates the production of a solid electrolyte havingexcellent soldering heat resistance (heat stability). In conventionallyknown capacitors using a solid electrolyte comprising polypyrrole or thelike, the capacitor properties greatly fluctuate at a high temperatureand a high humidity and the reliability is low. However, the capacitorcomprising a solid electrolyte formed with an electrically conductingcomposition of the present invention has excellent heat stability andexhibits good stability in the doped state, because the polymercomposition having the above-described anthracenemonosulfonate dopantand an other dopant derived from the oxidizing agent can be filled wellstep by step into the dielectric surface and even inside the pore, andthereby a structure where many thin films of the polymer composition areoverlaid one on another can be formed. As a result, a capacitor havingexcellent heat stability such that the dielectric film is prevented fromdamages by the polymer can be provided.

[0267] The charge transfer complex comprised anthracenemonosulfonate andπ electron-conjugated polymer is superior in thermal stability andstability in electric conductivity to the complex with conventionallyknown dopants (e.g., ClO₄ ⁻, BF₄ ⁻, Cl⁻, SO₄ ²⁻, benzensulfonate, etc.)because it is attributable to high aromaticity of the anthraceneskeleton and electron attractive property and water solubility of thesulfonic group and as a result can provide an excellent capacitorproperty.

[0268] The anthracenemonosulfonate used in the present invention is ageneric term of anthracenemonosulfonate compounds subsituted with asulfo group on the anthracene skeleton. Examples of preferred compoundsinclude unsubstituted anthracenesulfonate, or substituted compounds inwhich at least one of the hydrogen atoms on the anthracene ring ofanthracenesulfonic acid are substituted by linear or branched, saturatedor unsaturated C1-12, preferably C1-6, hydrocarbon group or alkoxygroup.

[0269] Specific examples of the compounds which donate theabove-mentioned unsubstituted anthracenemonosulfonate include anions ofanthracene-1-sulfonic acid, anthracene-2-sulfonic acid,anthracene-9-sulfonic acid, and their alkali metal salts, ammoniumsalts, etc. Specific examples of the subsituent of the substitutedanthracenemonosulfonate compound whose anthracene ring hydrogen(s) weresubsitutued include alkyl groups such as methyl, ethyl, propyl,isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, octyl, decyl, anddodecyl, unsaturated groups such as vinyl, allyl, 3-butenyl, and5-hexenyl, and methoxy, ethoxy, propyloxy, butoxy, pentoxy, hexyloxy,octyloxy, decyloxy, and dodecyloxy, etc.

[0270] The oxidizing agent for use in the present invention may be anyoxidizing agent suitable for the oxidation polymerization of pyrroles orthiophenes. Examples of the oxidizing agent which can be used includeoxidizing agents over a wide range, such as iron(III) chloride,Fe(ClO₄)₃, organic acid iron(III), inorganic acid iron(III),alkylpersulfate, ammonium persulfate, hydrogen peroxide and K₂Cr₂O₇described in JP-A-2-15611 (U.S. Pat. No. 4,910,645). Examples of theorganic acid of the organic acid iron(III) include a C1-20 alkylsulfonicacid such as methanesulfonic acid and dodecylbenzenesulfonic acid, and asimilar aliphatic carboxylic acid. However, the oxidizing agent may berestricted in the range of use by the chemical structure of the monomercompound represented by formula (VIII), the oxidizing agent, reactionconditions and the like. For example, according to Handbook ofConducting Polymers, page 99, Marcel Dekker, Inc. (1987), FIG. 5, thekind of the substituent greatly affects the oxidation potential (oneindex for showing whether the polymerization readily or difficultlyoccurs) and in turn, governs the oxidation (polymerization) ofthiophenes (oxidation potential expands over a wide range of from about1.8 to about 2.7 V). Accordingly, in practice, the combination of themonomer compound and oxidizing agent used and the reaction conditions isimportant.

[0271] The anion other than the anthracenemonosulfonate is a reducedchemical species anion after the reaction of the oxidizing agent andspecific examples thereof include chloride ion, ClO₄ ⁻, C1-12 aliphaticorganic carboxylate ion, sulfate ion phosphate ion, C1-12 aliphaticorganophosphate and borate. Furthermore, an electron acceptor dopantsuch as NO⁻ and NO₂ ⁺ salts (e.g., NOBF₄, NOPF₆, NOSbF₆, NOAsF₆,NOCH₃SO₃, NO₂BF₄, NO₂PF₆, NO₂CF₃SO₃) may also be used.

[0272] In the production method of a solid electrolytic capacitor of thepresent invention, the chemical polymerization of thiophene representedby formula (IX) is particularly preferably performed using persulfate.The use of iron(III) salt-based oxidizing agent has a problem in that aniron element remains and adversely affects the capacitor properties.Persulfates suitable for the monomer compound represented by formula(IX) are not suitable for the thiophene represented by formula (VIII)(R¹═R²═H, X═S) and thus, the use of the oxidizing agent has arestriction. Examples of the persulfate which can be particularlysuitably used for the chemical polymerization of a thiophene representedby formula (IX) include ammonium persulfate and potassium persulfate.

[0273] Preferred conditions for the producing (polymerization) reactionare described below.

[0274] The concentration of the monomer compound represented by formula(VIII) or preferably by formula (IX) for use in the production method ofa capacitor of the present invention and the concentrations of theoxidizing agent and the anthracenemonosulfonic acid used vary dependingon the kind of the compound or substituents thereof and the combinationwith a solvent or the like. However, it is in general from 1×10⁻⁴ to 10mol/l, preferably from 1×10⁻³ to 5 mol/l. The reaction temperature isselected according to respective reaction processes and cannot bespecifically limited, however, it is generally from −70 to 250° C.,preferably from 0 to 150° C. and more preferably from 15 to 100° C.

[0275] Examples of the solution for use in the production method of thepresent invention or the solvent for use in washing after thepolymerization include ethers such as tetrahydrofuran (THF), dioxane anddiethyl ether, ketones such as acetone and methyl ethyl ketone, aproticpolar solvents such as dimethylformamide (DMF), acetonitrile,benzonitrile, N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO),esters such as ethyl acetate and butyl acetate, nonaromatic chlorinatedsolvents such as chloroform and methylene chloride, nitro compounds suchas nitromethane, nitroethane and nitrobenzene, alcohols such asmethanol, ethanol and propanol, organic acids such as formic acid,acetic acid and propionic acid, acid anhydrides of the organic acid(e.g., acetic anhydride), water, and a mixed solvent thereof. Of these,preferred are water, alcohols, ketones and/or a combination thereof.

[0276] The solid electrolyte thus produced has an electric conductivityof from 0.1 to 200 S/cm, preferably from 1 to 100 S/cm, more preferablyfrom 10 to 100 S/cm.

[0277] In the present invention, for one part electrode, a knownmaterial such as a foil or bar having a valve action of aluminum,titanium, tantalum, niobium or an alloy using such a material as asubstrate, or a sintered body mainly comprising such a material. Thismetal electrode is used after treating the surface thereof by a knownmethod such as etching or chemical forming so as to increase thespecific surface area, and thereby forming a metal oxide film layer onthe metal foil.

[0278] The solid electrolyte is preferably formed by effecting theproducing process on the dielectric layer. In particular, a method ofchemically depositing an organic electric conductor having excellentheat resistance of the present invention on a dielectric material havinga porous or void structure is preferred. Furthermore, in order to attaingood electrical contacting, an electric conductor layer is preferablyprovided on the semiconductor and the electric conductor layer isformed, for example, by solidifying or plating an electricallyconducting paste, vapor deposition of a metal or forming an electricallyconducting resin film.

[0279] An example of the solid electrolytic capacitor product by thepresent invention is shown in FIG. 1 in a cross-sectional view. A basicdevice includes an oxide film (dielectric layer) (3) of an anodesubstrate composed of an etched metal foil (1), a solid semiconductor(solid electrolyte) (4) as an electrode opposite to the outside of theoxide film, and an electric conductor layer (5) formed from anelectrically conducting paste. A cathode lead terminal (7 a) isconnected to the metal foil (1) and an anode lead terminal (7 b) isconnected to the electric conductor layer (5). The whole device issealed with an insulating resin (6) such as an epoxy resin completelyand is further is jacketed with a resin mold, a resin case or ametal-made jacket case or by resin dipping and then the capacitor can beused as a product capacitor for various uses.

BEST MODE FOR CARRYING OUT THE INVENTION

[0280] Hereafter, this invention will be described in detail byexamples. However, the invention is by no means limited thereto.

EXAMPLE 1

[0281] On an etched, formed aluminum foil cut to 3 mm×10 mm was applieda polyimide tape of 1 mm wide so as to extend over both surfaces thereofso that it divides the foil into 4 mm and 5 mm portions. The 3 mm×4 mmportion of the etched, formed aluminum foil was subjected to forming at13V in an aqueous 10 wt % ammonium adipate solution to form an oxidedielectric film. Then, the 3 mm×4 mm portion of the aluminum foil wasdipped in an aqueous 30 wt % ammonium persulfate solution (solution 1)and taken out of the solution, followed by drying at 80° C. for 30minutes. Subsequently, the 3 mm×4 mm portion of the aluminum foil (theportion having formed thereon an oxide dielectric film) was dipped in anisopropanol solution containing 20 wt % 3,4-dioxyethylene-thiophene(solution 2) and taken out of the solution and left standing in anenvironment at 60° C. for 10 minutes, thereby completing the oxidativepolymerization. The substrate was dipped again in solution 1 andprocessed in the same manner as described above. The procedure from thedipping in solution 1 to the oxidative polymerization was repeated 10times and then the substrate was washed with warm water at 50° C. for 10minutes, followed by drying at 100° C. for 30 minutes to form anelectrically conducting polymer layer (solid electrolyte layer).

[0282] A scanning electron micrograph (at magnification of ×2,000) of across-section of the aluminum foil having formed thereon an electricallyconducting polymer layer thus obtained is shown in FIG. 2. FIG. 3 is anenlarged illustration (at a magnification of ×10,000) of the portionformed on an outer surface of microfine pore structure on the dielectricmaterial layer of the electrically conducting polymer layer shown inFIG. 2. FIG. 4 is a scanning electron micrograph (at a magnification of×50,000), illustrating the microfine pore portion shown in FIG. 3 in anenlarged view.

[0283] From these figures, it revealed that the electrically conductingpolymer covers in the form of a lamellar structure the surface insidethe microfine pores of dielectric material (alumina) on the metallicaluminum to form void spaces in the lamellar electrically conductingpolymer layer. The thickness of the electrically conducting polymerlayer formed on the outside surface of the microfine pore structure isabout 5 μm and the thickness per unit layer which constitutes thelamellar structure is in the range of about 0.1 to 0.3μm.

[0284] FIGS. 2 to 4, which are enlarged views of the microfine portionof the above-described aluminum foil, indicate that although theelectrically conducting polymer covers the entire surface inside themicrofine pores, there exist voids even in these covered portions.

[0285] Subsequently, the part of the aluminum foil on which theelectrically conducting polymer layer was formed was connected to a leadterminal of the cathode through carbon paste and silver paste and theportion on which no electrically conducting polymer layer was formed waswelded with a lead terminal of the anode of the element. These elementswere sealed with an epoxy resin to fabricate a capacitor device. Therated voltage was applied to the capacitor device thus fabricated and itwas aged at 125° C. for 2 hours. Thus, 30 capacitor devices in totalwere completed.

[0286] The 30 capacitor devices were measured for initialcharacteristics, i.e., capacitance (C) and tangent of loss angle (tanδ)(DF) at 120 Hz, impedance (Z) at a resonance frequency, and leakagecurrent (LC). The leakage current (LC) was measured one minute afterapplication of a rated voltage. Table 1 shows average values of themeasured values and fraction defective and number of shorted units whenthose having an LC of 0.16 μA (0.002 CV) or more are judged as a shortedproduct (defective). The average LC is calculated exclusive of thedefective units. Table 2 shows the results of reflow tests andsubsequent moisture resistance tests. In the moisture resistance tests,leakage current of 3.2 μA (0.04 CV) or more are judged as a defectiveunit. The reflow tests were carried out by passing samples through atemperature region at 230° C. for 30 minutes. The moisture resistancetests were carried out by leaving samples to stand at high temperatureand high humidity conditions of 85° C. and 85% RH for 500 hours.

Comparative Example 1

[0287] Thirty (30) capacitor devices were fabricated in the same manneras in Example 1 except for using the following method. That is, the 3mm×4 mm portion of the aluminum foil was dipped in an isopropanolsolution containing 20 wt % 3,4-dioxyethylene-thiophene (solution 2) andthen in an aqueous 30 wt % ammonium persulfate solution (solution 1).Then the foil was taken out and left standing in an environment at 60°C. for 10 minutes, thus completing the oxidative polymerization.Thereafter, the substrate was washed with warm water at 50° C. for 10minutes and dried at 100° C. for 30 minutes. The operations of thedipping in solution 2 and then solution 1, taking out and leavingstanding, washing with warm water, and drying were repeated 20 times toform an electrically conducting polymer layer. In the capacitor deviceof the instant comparative example, an electrically conducting polymerlayer of about 5 μm in thickness was formed on the outer surface ofmicrofine pore structure, but scanning electron micrograph indicated nolamellar structure like that in Example 1 (FIGS. 2 to 4). The evaluationof the characteristics of the capacitor devices were performed in thesame manner as in Example 1 and the results obtained are shown in Tables1 and 2.

EXAMPLE 2

[0288] Thirty (30) capacitor devices were fabricated in the same manneras in Example 1 except for using in Example 1 potassium persulfate inplace of ammonium persulfate and N-methylpyrrole in place of3,4-dioxyethylene-thiophene. Also in the electrically conducting polymerlayer of the capacitor device of this example, a lamellar structuresimilar to that in Example 1 (FIGS. 2 to 4) was observed and anelectrically conducting polymer layer formed on the outer surface ofmicrofine pore structure had a thickness of about 10 μm and a unit layerconstituting the lamellar structure had a thickness of about 0.1 to 0.5μm. Inside the microfine pore structure, there were observed void spacessimilar to those illustrated in FIG. 3. Evaluation of thecharacteristics of capacitor devices were performed in the same manneras in Example 1. The results obtained are shown in Tables 1 and 2.

Comparative Example 2

[0289] Thirty (30) capacitor devices were fabricated in the same manneras in Comparative Example 1 except for using in Comparative Example 1potassium persulfate in place of ammonium persulfate and N-methylpyrrolein place of 3,4-dioxyethylene-thiophene. Also in the electricallyconducting polymer layer of the capacitor device of this comparativeexample, a lamellar structure similar to that in Comparative Example 1was observed but there was observed no lamellar structure like that inExample 1 (FIGS. 2 to 4). The evaluation of the characteristics of thecapacitor devices were performed in the same manner as in Example 1 andthe results obtained are shown in Tables 1 and 2.

EXAMPLE 3

[0290] Thirty (30) capacitor devices were fabricated in the same manneras in Example 1 except for using the following method. That is, the 3mm×4 mm portion of the aluminum foil was dipped in a dioxane solutioncontaining 30 wt % 2,3-dichloro-5,6-dicyanobenzoquinone (solution 1) andtaken out and dried at 100° C. for 30 minutes. Subsequently, thealuminum foil was dipped in an isopropanol solution containing 20 wt %of isothianaphthene (solution 2) and taken out and left standing in anenvironment at 80° C. for 30 minutes, thus completing the oxidativepolymerization. Then, the operations of from the dipping in solution 1to the oxidative polymerization were repeated 10 times. Thereafter, thesubstrate was washed with dioxane at 50° C. for 10 minutes and dried at100° C. for 30 minutes to form an electrically conducting polymer layer.In the capacitor device of the instant example, a lamellar structuresimilar to that in Example 1 (FIGS. 2 to 4) was observed and anelectrically conducting polymer layer formed on the outer surface ofmicrofine pore structure had a thickness of about 20 μm and a unit layerconstituting the lamellar structure had a thickness of about 0.2 to 1μm. Inside the microfine pore structure, there were observed void spacessimilar to those illustrated in FIG. 3. Evaluation of thecharacteristics of capacitor devices were performed in the same manneras in Example 1. The results obtained are shown in Tables 1 and 2.

Comparative Example 3

[0291] Thirty (30) capacitor devices were fabricated in the same manneras in Comparative Example 1 except for using the following method. Thatis, the 3 mm×4 mm portion of the aluminum foil was dipped in anisopropanol solution containing 20 wt % isothianaphthene (solution 2)and then in a dioxane solution containing 30 wt %2,3-dichloro-5,6-dicyanobenzoquinone (solution 1). Then the foil wastaken out and left standing in an environment at 80° C. for 30 minutes,thus completing the oxidative polymerization. Thereafter, the substratewas washed with warm water at 50° C. for 10 minutes and dried at 100° C.for 30 minutes. The operations of the dipping in solution 2 and to thewashing and drying were repeated 20 times to form an electricallyconducting polymer layer. In the capacitor device of the instantcomparative example, an electrically conducting polymer layer of about15 μm in thickness was formed on the outer surface of microfine porestructure, but scanning electron micrograph indicated no lamellarstructure like that in Example 1 (FIGS. 2 to 4). The evaluation of thecharacteristics of the capacitor devices were performed in the samemanner as in Example 1 and the results obtained are shown in Tables 1and 2. TABLE 1 Initial Characteristics Ratio of Number of C DF Z LCDefective/Sample Short (μF) (%) (mΩ) (μA) (units/units) Circuit Example1 12.8 0.7 42 0.03 0/30 0 Example 2 12.3 0.9 34 0.05 0/30 0 Example 312.5 0.8 51 0.06 0/30 0 Comparative 12.4 1.4 78 0.11 2/30 1 Example 1Comparative 11.9 1.7 89 0.19 4/30 2 Example 2 Comparative 12.6 2.2 930.17 3/30 2 Example 3

[0292] TABLE 2 Reflow Test Humidity Resistance Test Number Number of ofDefective Short Defective Short Rate Circuit LC (μA) Rate CircuitExample 1 0/30 0 0.49 0/30 0 Example 2 0/30 0 0.54 1/30 0 Example 3 0/300 0.59 0/3  0 Comparative 4/28 2 1.53 3/24 2 Example 1 Comparative 7/265 1.94 8/21 5 Example 2 Comparative 6/27 3 1.68 5/24 3 Example 3

EXAMPLE 4

[0293] An aluminum foil having a purity of 99.99% and a thickness of 100μm was used as an anode and the surface thereof was electrochemicallyetched by an ordinary method to prepare a porous aluminum foil. Theporous aluminum foil obtained was subjected to formation in an ammoniumadipate solution to form an aluminum oxide layer as a dielectric thinfilm on the aluminum foil and then boiled in hot water to again effectformation to homogenize the dielectric thin film. The thus-preparedaluminum foil was thoroughly dried and coated with an aqueous solutionof 0.1M ferric sulfate as an oxidizing agent on the porous surface, andthen dried under heating (at a temperature of 80° C.) to support andactivate the oxidizing agent. Thereafter, the aluminum foil was dippedin an ethanol solution having dissolved therein 5 g of1,3-dihydroisothianaphthene and 0.1 g of sodium dodecylbenzenesulfonate(hereinafter simply referred to as “DBSNa”) and heated at 80° C. for 10minutes in a vapor phase. This in-situ polymerization accompanied by theevaporation of solvent was repeated 20 times to produce a polymercomposition. The polymer composition deposited on the surface was verycarefully measured on the electric conductivity by a four-probe methodand found to be 50 S/cm. The capacitor device thus manufactured wasmeasured on the properties and the results obtained are shown in Table3. The capacitance and tan δ are the values at a frequency of 120 Hz andthe impedance is a value at 1,000 KHz.

Comparative Example 4

[0294] An aluminum foil subjected to formation in the same manner as inExample 4 was dipped in a three-component mixed solution (the monomer,oxidizing agent and dopant were the same) adjusted so that eachcomponent had the same concentration as in Example 4 and immediately thein-situ polymerization by heating at 80° C. for 10 minutes was repeated20 times to manufacture a capacitor device. The electric conductivity onthe surface was carefully measured by a four-probe method and found tobe 10⁻² S/cm. However, the capacitor formed there from had a smallcapacitance and the capacitor properties were not satisfied. Theproperties of the capacitor are shown together in Table 3.

EXAMPLE 5

[0295] A capacitor device was manufactured by the same production methodexcept for using 1,3-dihydronaphtho[2,3-c]thiophene in place of1,3-dihydroisothianaphthene used in Example 4. The polymer compositiondeposited on the surface had an electric conductivity of 20 S/cm (by afour-probe method). The capacitor properties were also measured in thesame manner. The results obtained are shown in Table 3.

EXAMPLE 6

[0296] A capacitor device was manufactured through the same processexcept for using 5,6-dioxymethylene-1,3-dihydro-isothianaphthene inplace of 1,3-dihydroisothianaphthene used in Example 4 and using amonomer solution not containing the dopant (DBSNa) described in Example4. The processing conditions in the in-situ polymerization were 50° C.and 10 minutes. The polymer composition deposited on the surface had anelectric conductivity of 80 S/cm (by a four-probe method). The capacitorproperties obtained are shown in Table 3.

Comparative Example 5

[0297] An aluminum foil prepared in the same manner as in Example 4 wasdipped in a mixed component solution containing the same monomer andoxidizing agent as in Example 6 adjusted so that each component had thesame concentration as in Example 6, and then the processing wasperformed under the same conditions (50° C., 10 minutes) in the samerepetitions as in Example 6 to manufacture a capacitor device. Theelectric conductivity on the surface was 0.1 S/cm. The capacitorproperties obtained are shown in Table 3. With respect to the capacitorproperties, the capacitance was small.

EXAMPLE 7

[0298] A capacitor device was manufactured by the same production methodas in Example 4 except for using 1,3-dihydrothieno[3,4-b]quinoxaline inplace of 1,3-dihydroisothianaphthene used in Example 4 and using sodiumnaphthalenesulfonate (hereinafter simply referred to as “NSNa”) in placeof DBSNa as a dopant. The polymer composition deposited on the surfacehad an electric conductivity of 5 S/cm (by a four-probe method). Thecapacitor properties were measured and the data obtained are shown inTable 3.

EXAMPLE 8

[0299] A capacitor device was manufactured by the same production methodas in Example 4 except for using5,6-dimethoxy-1,3-dihydroisothianaphthene in place of1,3-dihydroisothianaphthene used in Example 4 and using NSNa in place ofDBSNa. The polymerization temperature and time were changed to 70° C.and 20 minutes. The polymer composition deposited on the surface had anelectric conductivity of 80 S/cm (by a four-probe method). The capacitorproperties were measured and the results obtained are shown in Table 3.TABLE 3 Capacitor Properties LC C(μF) DF(%) (μA · 10 V value) Z(Ω)Example 4 9.9 0.88 0.09 0.078 Example 5 9.8 0.92 0.08 0.092 Example 610.1  0.80 0.08 0.052 Example 7 9.9 0.95 0.06 0.080 Example 8 10.2  0.860.06 0.055 Comparative 4.8 2.50 10.50  0.95  Example 4 Comparative 6.72.30 8.65 0.67  Example 5

[0300] Property Test 1

[0301] The every 10 capacitors manufactured according to the productionmethods of Examples 4 to 8, Comparative Examples 4 and 5 were subjectedto reflow tests by passing a region at a temperature of 230° C. for 30seconds and compared on the properties between before and after thereflow processing. The results obtained are shown in Table 4. TABLE 4Results of Test on Reflow Heat Resistance (number of products acceptedper 10 devices) Before Reflow After Reflow Processing Processing Deviceproduced in Example 4 10 10 Device produced in Example 5  9  7 Deviceproduced in Example 6 10  9 Device produced in Example 7 10 10 Deviceproduced in Example 8 10 10 Device produced in Comparative  3  0 Example4 Device produced in Comparative  2  1 Example 5

Reference Example 1

[0302] 1,3-dihydroisothianaphthene monomer (melting point: 23° C.) wassolution-polymerized in nitrobenzene at 50° C. in the presence of oxygenand ferric chloride (oxidizing agent) according to the method describedin Synthetic Metals, Vol. 16, pp. 379-380 (1986) and the polymerobtained was measured on the electric conductivity. The electricconductivity was as low as 0.1 S/cm and the polymer was not suitable forthe solid electrolyte of a capacitor.

EXAMPLE 9

[0303] A capacitor device was manufactured through the same process asin Example 4 except for using 1,3-dihydro-isothianaphthene-2-oxide inplace of 1,3-dihydroisothianaphthene used in Example 4. The polymercomposition deposited on the surface was very carefully measured on theelectric conductivity by a four-probe method and found to be 70 S/cm.The capacitor device thus manufactured was measured on the propertiesand the results obtained are shown in Table 5. The capacity and tan δare the values at a frequency of 120 Hz and the impedance is a value at1,000 KHz.

Comparative Example 6

[0304] An aluminum foil prepared in the same manner as in Example 9 wasdipped in a mixed component solution containing the same monomer,oxidizing agent, and dopant as in Example 9 adjusted so that eachcomponent had the same concentration as in Example 9, immediatelyfollowed by conducting in-situ polymerization 20 times repeatedly byheating at 80° C. for 10 minutes to manufacture a capacitor device. Theelectric conductivity on the surface was carefully measured by afour-probe method and found to be 10⁻² S/cm. However, the capacitorformed therefrom had a small capacitance and the capacitor propertieswere insufficient as shown together in Table 5.

EXAMPLE 10

[0305] A capacitor device was manufactured by the same production methodexcept for using 1,3-dihydronaphtho[2,3-c]thiophene-2-oxide in place of1,3-dihydroisothianaphthene-2-oxide used in Example 9. The polymercomposition deposited on the surface had an electric conductivity of 10S/cm (by a four-probe method). The capacitor properties were measuredand the data obtained are shown in Table 5.

EXAMPLE 11

[0306] A capacitor device was manufactured by the same process exceptfor using 5,6-dioxymethylene-1,3-dihydroisothianaphthene-2-oxide inplace of 1,3-dihydroisothianaphthene-2-oxide used in Example 9 and usingthe monomer solution described in that example (DBSNa) but from whichthe dopant described was eliminated. The in-situ polymerizationconditions were 50° C. and 10 minutes. The polymer composition depositedon the surface had an electric conductivity of 100 S/cm (by a four-probemethod). The capacitor properties were measured and the data obtainedare shown in Table 5.

Comparative Example 7

[0307] An aluminum foil prepared in the same manner as in Example 9 wasdipped in a mixed component solution containing the same monomer andoxidizing agent as in Example 11 adjusted so that each component werethe same and had the same concentration as in Example 11, followed byconducting the treatment in the same times at the same temperature (50°C.) for the same time (10 minutes) to manufacture a capacitor device.The polymer composition deposited on the surface had an electricconductivity of 0.05 S/cm. However, the capacitor formed therefrom had asmall capacitance as shown together in Table 5.

EXAMPLE 12

[0308] A capacitor device was manufactured by the same production methodas in Example 9 except for using1,3-dihydrothieno[3,4-b]quinoxaline-2-oxide in place of1,3-dihydroisothianaphthene-2-oxide used in Example 9 and using NSNa asthe dopant in stead of DBSNa. The polymer composition deposited on thesurface had an electric conductivity of 1 S/cm (by a four-probe method).The capacitor properties were measured and the data obtained are shownin Table 5.

EXAMPLE 13

[0309] A capacitor device was manufactured by the same production methodas in Example 9 except for using5,6-dimethoxy-1,3-dihydroisothianaphthene-2-oxide in place of1,3-dihydroisothianaphthene-2-oxide used in Example 9 and using NSNa instead of DBSNa. The polymerization temperature and time were changed to70° C. and 20 minutes, respectively. The polymer composition depositedon the surface had an electric conductivity of 100 S/cm (by a four-probemethod). The results of measurement of capacitor properties are as shownin Table 5. TABLE 5 Capacitor Properties C (μF) DF (%) LC (μA · 10 Vvalue) Z (Ω) Example 9 10.2  0.83 0.08 0.070 Example 10 9.3 0.95 0.090.080 Example 11 9.9 0.90 0.09 0.060 Example 12 9.3 0.92 0.07 0.075Example 13 9.9 0.88 0.09 0.050 Comparative 6.2 2.54 10.30  0.99  Example6 Comparative 3.5 2.45 9.35 0.72  Example 7

[0310] Property Test 2

[0311] The every 10 capacitors manufactured according to the productionmethods of Examples 9 to 13, Comparative Examples 6 and 7 were subjectedto, ref low tests by passing a region at a temperature of 230° C. for 30seconds and compared on the properties between before and after thereflow processing. The results obtained are shown in Table 6. TABLE 6Results of Test on Reflow Heat Resistance (number of products acceptedper 10 devices) Before Reflow After Reflow Processing Processing Deviceproduced in Example 9 10 9 Device produced in Example 10 10 8 Deviceproduced in Example 11 10 10  Device produced in Example 12 10 8 Deviceproduced in Example 13 10 10  Device produced in Comparative  2 0Example 6 Device produced in Comparative  3 0 Example 7

Reference Example 2

[0312] A 1,3-dihydroisothianaphthene-2-oxide monomer was polymerized inthe presence of sulfuric acid at room temperature according to themethod described in J. Org. Chem., Vol. 49, pp. 3382 (1984) and thepolymer obtained was measured on the electric conductivity. The electricconductivity was as low as 0.5 S/cm and the polymer was not preferablefor the solid electrolyte of a capacitor.

EXAMPLE 14

[0313] A formed aluminum foil was subjected to forming at 13 V in anaqueous 10 wt % ammonium adipate solution to prepare a dielectricmaterial thereon. The surface of this dielectric material wasimpregnated with an aqueous solution prepared to have an ammoniumpersulfate (hereinafter simply referred to as “APS”) concentration of 20wt % and a sodium 1-naphthalenesulfonate concentration of 0.1 wt %, andthen the dielectric material was dipped in an isopropanol (hereinaftersimply referred to as “IPA”) solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene. The resulting substrate was left standingin an environment at 60° C. for 10 minutes, thereby completing theoxidation polymerization, and then washed with water. Thispolymerization reaction and washing process each was repeated 10 times.The polymer composition was reduced by hydrazine in a water/IPA solventand then carefully extracted with the solvent and the contents ofsulfate ion and 1-naphthalenesulfonate ion in the polymer compositionwere determined by ion chromatography method. As a result, the sulfateion content was 1.3 wt % and the 1-naphthalenesulfonate ion content was33 wt %, based on the dry weight of the polymer composition.

[0314] Thereafter, an aluminum foil having accumulated thereon thepolythiophene polymer composition was treated in an aqueous 10 wt %ammonium adipate solution and then examined on the sparking voltage. Thetest was performed 5 times (n=5) in an environment of 50° C. under theconditions of a current density of 10 mA/cm². The results obtained areshown in Table 7. Subsequently, the aluminum core part was welded with aplus side lead terminal for collecting the current from the anode and onthe other hand, connected to the minus side lead terminal through carbonpaste and silver paste for collecting the current from the cathode.These elements were sealed by an epoxy resin to manufacture a capacitordevice. The capacitor device manufactured was aged at 125° C. for 2hours and then determined on the initial characteristics. The resultsobtained are shown together in Table 8. These were each measured at 120Hz. The impedance (Z) is shown by a value at a resonance frequency. LC(leakage current) was measured one minute after application of a ratedvoltage. The measured values each is an average of 30 samples. Withrespect to LC, those having an LC of 1 μA or more are judged as ashorted product (defective) and the average LC is calculated exclusiveof the defective units.

EXAMPLE 15

[0315] A capacitor device was prepared and evaluated in the same manneras in Example 14 except for using potassium persulfate in place of APSused in Example 14 and preparing a solution having a potassium sulfateconcentration of 10 wt % and a sodium 1-naphthalenesulfonateconcentration of 0.1 wt %. The results obtained are shown in Tables 7and 8. The contents of sulfate ion and 1-naphthalenesulfonate ion in thepolymer composition were determined by the method described in Example14 and it was found that the sulfate ion content was 2.1 wt % and the1-naphthalenesulfonate ion content was 29.5 wt %.

EXAMPLE 16

[0316] A capacitor device was prepared and evaluated in the same manneras in Example 14 except for preparing a solution by changing theconcentration of APS used in Example 14 from 20 wt % to 35 wt % and theconcentration of sodium 1-naphthalenesulfonate from 0.1 wt % to 0.04 wt%. The results obtained are shown in Tables 7 and 8. The contents ofsulfate ion and 1-naphthalenesulfonate ion in the polymer compositionwere determined by the method described in Example 14 and it was foundthat the sulfate ion content was 4.7 wt % and the 1-naphthalenesulfonateion content was 9.5 wt %.

Comparative Example 8

[0317] A capacitor device was prepared and evaluated in the same manneras in Example 14 except for using ferric sulfate in place of APS used inExample 14 and preparing a solution having a ferric sulfateconcentration of 10 wt % and a sodium 1-naphthalenesulfonateconcentration of 0.1 wt %. The results obtained are shown in Tables 7and 8. The contents of sulfate ion and 1-naphthalenesulfonate ion in thepolymer composition were determined by the method described in Example14 and it was found that the sulfate ion content was 20.5 wt % and the1-naphthalenesulfonate ion content was 36.8 wt %. Since 8 wt % of ironion (ferric and ferrous ions) was also present and the sulfate ioncontent exceeded 10 wt %, the capacitor had poor properties.

Comparative Example 9

[0318] A capacitor device was prepared and evaluated in the same manneras in Example 14 except for using ferric chloride in place of APS usedin Example 14 and preparing a solution having a ferric chlorideconcentration of 10 wt % and a sodium 1-naphthalenesulfonateconcentration of 0.1 wt %. The results obtained are shown in Tables 7and 8. The content of 1-naphthalensulfonate ion in the polymercomposition was determined by the method described in Example 14 andfound to be 4.5 wt %. Since sulfate ion was not used in combination, thead poor properties.

Comparative Example 10

[0319] A process for manufacturing a capacitor device was performedunder the same conditions as in Example 14 except for using thiophene inplace of 3,4-dioxyethylene-thiophene used in Example 14. However, blackblue polythiophene polymer was not produced at all and thus,polymerization of thiophene was not caused by the action of APS. Inother words, occurrence of the oxidation polymerization of a thiopheneby APS was 3,4-dioxy-ethylene group-substituted thiophenes. TABLE 7Sparking Voltage (unit: V. n = 5) Comparative Number of Example ExampleReaction Times 14 15 16 8 9 1 29 25 2 32 35 32 25 20 3 22 16 4 29 31 2821  2 5  9 6 29 30 28  3 8 28 29 28 10  28 29 28

[0320] TABLE 8 Initial Characteristics Number Ratio of of C DF Z LCDefective/Sample Short (μF) (%) (mΩ) (μA) (units/units) Circuit Example14 5.3 0.8 15 0.03 0/30 0 Example 15 5.0 0.9 21 0.04 2/30 0 Example 165.2 0.7 23 0.06 1/30 0 Comparative 4.7 1.8 65 0.03 16/30  9 Example 8Comparative 4.0 3.4 355  0.45 28/30  17  Example 9

[0321] As being apparent from Table 7, in the sparking voltage test ofExamples 14 to 16, although the voltage was greatly reduced at theinitial stage, the sparking voltage at the completion of the reactionwas 27 V or more in each Example. In Comparative Example 8 using ferricsulfate, the sparking voltage was largely reduced due to remaining ofiron ion (ferric and ferrous ions) in a concentration as high as 8 wt %and the sparking voltage could not withstand until the prescribedreaction was completed. As a result, the solid electrolyte wasinsufficiently filled and this was disadvantageous.

EXAMPLE 17

[0322] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material on the aluminum foil. Thesurface of this dielectric material was impregnated with an aqueoussolution prepared to have an APS concentration of 20 wt % and a sodiumanthraquinone-2-sulfonate concentration of 0.1 wt %, and then thedielectric foil was dipped in 1.2 mol/l of an IPA solution havingdissolved therein 5 g of 3,4-dioxyethylene-thiophene. The resultingsubstrate was taken out and left standing in an environment at 60° C.for 10 minutes, thereby completing the oxidative polymerization, andthen the substrate was washed with water. This polymerization reactionand washing process each was repeated 10 times. The polymer compositionwas reduced by hydrazine in a water/IPA solvent and then carefullyextracted and the contents of sulfate ion and anthraquinone-2-sulfonateion in the polymer composition were determined by ion chromatographymethod. As a result, the sulfate ion content was 1.1 wt % and theanthraquinone-2-sulfonate ion content was 34 wt %, based on the dryweight of the polymer composition. The solid electrolyte layer had anelectric conductivity of 75 S/cm.

[0323] Thereafter, an aluminum foil having deposited thereon thepolythiophene composition was treated in an aqueous 10 wt % ammoniumadipate solution and then examined on the sparking voltage. The test wasperformed by increasing the number of devices (the same in the followingExamples) so as to attain distinguished comparison of the deviceproperties, namely, in an environment of 50° C. under the conditions ofa current density of 10 mA/cm² in n=5 times. The results obtained areshown in Table 9. Subsequently, the aluminum core part was welded with aplus side lead terminal for collecting the current from the anode and onthe other hand, connected to the minus side lead terminal through carbonpaste and silver paste for collecting the current from the cathode.These elements were finally sealed by an epoxy resin to manufacture acapacitor device. The capacitor device manufactured was aged at 125° C.for 2 hours and then subjected to the initial evaluation. The resultsobtained are shown together in Table 10. In the Table, C in the columnof initial characteristics indicates a capacitance and DF indicates atangent of the loss angle (tan δ). These were each measured at 120 Hz.The impedance is shown by a value at a resonance frequency. LC (leakagecurrent) was measured one minute after applying a rated voltage. Themeasured values each is an average of 30 samples. With respect to LC,those having an LC of 1 μA or more are judged as a defective and thosehaving an LC of 10 μA or more are judged as a shorted product. Theaverage LC is calculated exclusive of the defective units.

EXAMPLE 18

[0324] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material. The surface of thisdielectric material was impregnated with an aqueous solution prepared tohave an APS concentration of 20 wt % and then dipped in an IPA/watermixed solution prepared by adding ammonium anthraquinone-2,6-disulfonateto 1.2 mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene to have an ammoniumanthraquinone-2,6-disulfonate concentration of 0.1 wt %. The resultingsubstrate was taken out and left standing in an environment at 60° C.for 10 minutes, thereby completing the oxidative polymerization, andthen the substrate was washed with water. This polymerization reactionand washing process each was repeated 10 times. The capacitor deviceobtained was evaluated. The results obtained are shown in Tables 9 and10. The contents of sulfate ion and anthraquinone-2,6-disulfonate ion inthe polymer composition were determined by the method described inExample 17. As a result, the sulfate ion content was 1.3 wt % and theanthraquinone-2,6-disulfonate ion content was 31 wt %. The solidelectrolyte layer had an electric conductivity of 80 S/cm.

EXAMPLE 19

[0325] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material. This dielectric material wasdipped in 1.2 mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene and then dipped in an aqueous solutionprepared to have an APS concentration of 20 wt % and a sodium1,4-naphthoquinone-2-sulfonate concentration of 0.1 wt %. The resultingsubstrate was taken out and left standing in an environment at 60° C.for 10 minutes, thereby completing the oxidative polymerization, andthen the substrate was washed with water. This polymerization reactionand washing process each was repeated 10 times. The capacitor deviceobtained was evaluated and the results obtained are shown in Tables 9and 10. The contents of sulfate ion and 1,4-naphthoquinone-2-sulfonateion in the polymer composition were determined by the method describedin Example 17. As a result, the sulfate ion content was 1.0 wt % and the1,4-naphthoquinone-2-sulfonate ion content was 28 wt %. The solidelectrolyte layer had an electric conductivity of 68 S/cm.

EXAMPLE 20

[0326] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V In an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material. The surface of thisdielectric material was impregnated with an aqueous solution prepared tohave a potassium persulfate concentration of 10 wt % and a sodiumanthraquinone-2-sulfonate concentration of 0.1 wt % and then dipped in1.2 mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene. The resulting substrate was taken out andleft standing in an environment at 60° C. for 10 minutes, therebycompleting the oxidative polymerization. This polymerization reactioncomprising the above process was repeated 10 times and then thesubstrate was washed with water and dried. The capacitor device obtainedwas evaluated and the results obtained are shown in Tables 9 and 10. Thecontents of sulfate ion and anthraquinonesulfonate ion in the polymercomposition were determined by the method described in Example 17. As aresult, the sulfate ion content was 2.0 wt % and theanthraquinone-2-sulfonate ion content was 30.0 wt %. The solidelectrolyte layer had an electric conductivity of 69 S/cm.

EXAMPLE 21

[0327] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material. The surface of thisdielectric material was impregnated with an aqueous solution prepared tohave an APS concentration of 35 wt % and then dipped in an IPA/watermixed solution having an ammonium anthraquinone-2,6-disulfonateconcentration of 0.04 wt % prepared by adding ammoniumanthraquinone-2,6-disulfonate to an IPA solution of 1.2 mol/l havingdissolved therein 5 g of 3,4-dioxyethylene-thiophene. The resultingsubstrate was taken out and left standing in an environment at 60° C.for 10 minutes, thereby completing the oxidative polymerization. Thispolymerization reaction comprising the above process was repeated 10times and then the substrate was washed with water and dried. Thecapacitor device obtained was evaluated and the results obtained areshown in Tables 9 and 10. The contents of sulfate ion andanthraquinone-2,6-disulfonate ion in the polymer composition weredetermined by the method described in Example 17. As a result, thesulfate ion content was 4.5 wt % and the anthraquinone-2,6-disulfonateion content was 9.2 wt %. The solid electrolyte layer had an electricconductivity of 50 S/cm.

EXAMPLE 22

[0328] A formed aluminum foil was processed to have a prescribed areaand then subjected to forming at 13 V in an aqueous 10 wt % ammoniumadipate solution to prepare a dielectric material. This dielectricmaterial was dipped in a degassed IPA solution of5,6-dimethoxy-isothianaphthene synthesized and produced by sublimationaccording to the method described in JP-A-2-242816 wherein theconcentration of the compound was 1.2 mol/l and then dipped in 20 wt %of aqueous APS solution of sodium3-methyl-2-anthraquinolylmethanesulfonate synthesized according to themethod described in Tetrahedron, Vol. 35, No. 19, page 2263 (1979)wherein the concentration of the sodium3-methyl-2-anthraquinolylmethanesulfonate was adjusted to be 0.1 wt % inthe aqueous solution. The resulting substrate was taken out and leftstanding in an environment at 60° C. for 10 minutes, thereby completingthe oxidative polymerization. This polymerization reaction comprisingthe above process was repeated 10 times and then the substrate waswashed with water and dried. The capacitor device obtained was evaluatedand the results obtained are shown in Tables 9 and 10. The contents ofsulfate ion and 3-methyl-2-anthraquinolylmethanesulfonate ion in thepolymer composition were determined by the method described in Example17. As a result, the sulfate ion content was 0.5 wt % and the3-methyl-2-anthraquinolylmethanesulfonate ion content was 4.8 wt %. Thesolid electrolyte layer had an electric conductivity of 40 S/cm.

EXAMPLE 23

[0329] A capacitor device was prepared and evaluated in the same manneras in Example 17 except for using a solution of pyrrole-N-methylprepared to have the same concentration in place of3,4-dioxyethylene-thiophene used in Example 1. The results obtained areshown in Tables 9 and 10. The contents of sulfate ion andanthraquinone-2-sulfonate ion in the polymer composition were determinedby the method described in Example 17. As a result, the sulfate ioncontent was 7.5 wt % and the anthraquinone-2-sulfonate ion content was20.3 wt %. The solid electrolyte had an electric conductivity of 8 S/cm.

EXAMPLE 24

[0330] A formed aluminum foil was processed to have a prescribed areaand then subjected to forming at 13 V in an aqueous 10 wt % ammoniumadipate solution to prepare a dielectric material. This dielectricmaterial was dipped in a 30% DMF-IPA solution prepared to have a sodiumanthraquinone-2-sulfonate concentration of 0.1 wt % and a3,4-dioxyethylene-thiophene concentration of 1.2 mol/l and then dippedin a 20 wt % aqueous APS solution. The resulting substrate was taken outand left standing in an environment at 60° C. for 10 minutes, therebycompleting the oxidative polymerization. These dipping processes eachwas repeated 10 times and then the substrate was washed with water anddried. The capacitor device obtained was evaluated and the resultsobtained are shown in Tables 9 and 10. The sulfate ion content was 1.2wt % and the anthraquinone-2-sulfonate ion content was 37 wt %, based onthe dry weight of the polymer composition. The solid electrolyte layerhad an electric conductivity of 80 S/cm.

Reference Example 3

[0331] A process for manufacturing a capacitor device was performedunder the same conditions as in Example 17 except for using thiophene inplace of 3,4-dioxyethylene-thiophene used in Example 17. However, blackblue polythiophene was not produced at all and thus, polymerization ofthiophene was not caused by the action of APS. In other words,occurrence of the oxidation polymerization of a thiophene by APS waspeculiar to 3,4-dioxy group-substituted thiophenes.

Comparative Example 10

[0332] A formed dielectric material was prepared in the same manner asin Example 17 and the dielectric material obtained was dipped in a 12%IPA solution of ferric anthraquinone-2-sulfonate and then dipped in 1.2mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene. The resulting substrate was left standingin an environment at 60° C. for 10 minutes, thereby completing theoxidative polymerization, and then the substrate was washed with water.This polymerization reaction and washing process each was repeated 10times. The polymer composition was reduced by hydrazine in a water/IPAsolvent and then carefully extracted and the content ofanthraquinone-2-sulfonate ion in the polymer composition was determinedby ion chromatography method. As a result, the anthraquinone-2-sulfonateion content was 25 wt % based on the dry weight of the polymercomposition. The solid electrolyte layer had an electric conductivity of30 S/cm. Thereafter, a capacitor device was manufactured and examined onthe sparking voltage and other capacitor properties in the same manneras in Example 17. The results obtained are shown in Tables 9 and 10.

Comparative Example 11

[0333] A capacitor device was prepared and evaluated in the same manneras in Example 17 except for changing the concentration of APS used inExample 17 from 20 wt % to 12 wt %. The results obtained are shown inTables 9 and 10. The contents of sulfate ion andanthraquinone-2-sulfonate ion in the polymer composition were determinedby the method described in Example 17. As a result, the sulfate ioncontent was 0.09 wt % and the anthraquinone-2,6-disulfonate ion contentwas 32 wt %. The solid electrolyte had an electric conductivity of 40S/cm.

Comparative Example 12

[0334] A capacitor device was prepared and evaluated in the same manneras in Example 17 except for using a solution prepared to have a ferricsulfate concentration of 10 wt % and a sodium anthraquinone-2-sulfonateconcentration of 0.1 wt % in place of APS used in Example 17. Theresults obtained are shown in Tables 9 and 10. The contents of sulfateion and anthraquinone-2-sulfonate ion in the polymer composition weredetermined by the method described in Example 17. As a result, thesulfate ion content was 20.0 wt % and the anthraquinonesulfonate ioncontent was 37.8 wt %. In the polymer composition, 8 wt % of iron ion(ferric and ferrous) was present and the sulfate ion content exceeded 10wt %, as a result, the capacitor exhibited poor properties.

Comparative Example 13

[0335] A capacitor device was prepared and evaluated in the same manneras in Example 17 except for using thiophene in place of3,4-dioxyethylene-thiophene used in Example 17 and preparing a solutionto have a concentration of ferric chloride used in place of APS, of 10wt % and a sodium anthraquinone-2-sulfonate concentration of 0.1 wt %.The results obtained are shown in Tables 9 and 10. Theanthraquinone-2-sulfonate ion content in the polymer composition wasdetermined by the method described in Example 17 and found to be 4.2 wt%. Since sulfate ion was not used in combination, the capacitorexhibited poor properties. TABLE 9 Sparking Voltage (unit: V, n = 5)Number of Reaction Times 1 2 3 4 5 6 8 10 Example 17 19 19 19 19 19 1919 19 Example 18 19 19 19 19 19 19 19 19 Example 19 19 19 19 19 19 19 1919 Example 20 19 19 19 18 17 15 13 10 Example 21 19 19 19 19 19 19 19 19Example 22 19 19 19 19 19 19 19 19 Example 23 19 19 19 19 19 19 19 19Example 24 19 19 19 19 19 19 19 19 Comparative 19 16 13 5 2 Example 10Comparative 19 19 19 19 19 19 19 19 Example 11 Comparative 19 17 13 3Example 12 Comparative 18 15 11 3 Example 13

[0336] TABLE 10 Initial Characteristics Ratio of C DF Z LCDefective/Sample Short (μF) (%) (mΩ) (μA) Circuit Example 17 8.0 0.7 600.02 0/30 0 Example 18 8.2 0.7 60 0.02 0/30 0 Example 19 7.5 0.8 60 0.030/30 0 Example 20 7.0 0.8 60 0.04 1/30 0 Example 21 6.9 0.9 60 0.05 1/300 Example 22 6.8 0.8 60 0.05 1/30 0 Example 23 4.1 1.2 60 0.09 1/30 0Example 24 8.1 0.7 60 0.02 1/30 0 Comparative 7.1 1.2 60 0.15 10/30  8Example 10 Comparative 7.0 0.7 60 0.09 1/30 0 Example 11 Comparative 6.13.2 83 0.40 15/30  10  Example 12 Comparative 5.9 3.3 90 0.43 27/30  18 Example 13

[0337] As will be apparent from Table 9, in the sparking voltage test ofExamples 17 to 24, substantially no decrease in voltage was observed atthe initial stage, the sparking voltage at the completion of thereaction was 19 V or less in each Example. In Comparative Example 12using ferric sulfate, the sparing voltage was largely reduced due toremaining of iron ion (ferric and ferrous ions) in a concentration ashigh as 8 wt % and the sparking voltage could not withstand until theprescribed reaction was completed. As a result, the solid electrolytewas insufficiently filled and this was disadvantageous.

EXAMPLE 25

[0338] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material on the aluminum foil. Thesurface of this dielectric material was impregnated with an aqueoussolution prepared to have an ammonium persulfate concentration of 20 wt% and a sodium anthracene-2-sulfonate (manufactured by Salor Co.)concentration of 0.3 wt %, and then the dielectric foil was dipped in1.2 mol/l of IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene. The resulting substrate was taken out andleft standing in an environment at 60° C. for 10 minutes, therebycompleting the oxidative polymerization, and then the substrate waswashed with water. This polymerization reaction and washing process eachwas repeated 10 times. The polymer composition was reduced by hydrazinein a water/IPA solvent and then carefully extracted and the contents ofsulfate ion and anthracene-2-sulfonate ion in the polymer compositionwere determined by ion chromatography method. As a result, the sulfateion content was 1.7 mol % and the anthracene-2-sulfonate ion content was14.6 mol %, based on the dry weight of the polymer composition. Thesolid electrolyte layer had an electric conductivity of 70 S/cm.

[0339] Thereafter, an aluminum foil having deposited thereon thepolythiophene composition was treated in an aqueous 10 wt % ammoniumadipate solution and then examined on the sparking voltage. The test wasperformed by increasing the number of devices (the same in the followingExamples) so as to attain distinguished comparison of the deviceproperties, namely, in an environment of 50° C. under the conditions ofa current density of 10 mA/cm² in n=5 times. The results obtained areshown in Table 11. Subsequently, the aluminum core part was welded witha plus side lead terminal for collecting the current from the anode andon the other hand, connected to the minus side lead terminal throughcarbon paste and silver paste for collecting the current from thecathode. These elements were finally sealed by an epoxy resin tomanufacture a capacitor device. The capacitor device manufactured wasaged at 125° C. for 2 hours and then subjected to the initialevaluation. The results obtained are shown together in Table 12. In theTable, C in the column of initial characteristics indicates acapacitance and DF indicates a tangent of the loss angle (tan δ). Thesewere each measured at 120 Hz. The impedance is shown by a value at aresonance frequency. LC (leakage current) was measured one minute afterapplying a rated voltage. The measured values each is an average of 30samples. With respect to LC, those having an LC of 1 μA or more arejudged as a defective and those having an LC of 10 μA or more are judgedas a shorted product. The average LC is calculated exclusive of thedefective units.

EXAMPLE 26

[0340] A dielectric material was prepared by the method described inExample 25 and the surface of the dielectric material was impregnatedwith an aqueous solution prepared to have an APS concentration of 20 wt% and then dipped in an IPA/water mixed solution prepared by addingtetrabutylammonium 9,10-dimethoxy-anthracene-2-sulfonate (hereafter,abbreviated as DMASTB) to 1.2 mol/l of an IPA solution having dissolvedtherein 5 g of 3,4-dioxyethylene-thiophene to have a DMASTBconcentration of 0.1 wt %. The above-mentioned DMASTB salt used wasprepared by mixing sodium 9,10-dimethoxy-anthracene-2-sulfonate(manufactured by Aldrich Co.) with tetrabutylammonium bromide andrecrystallizing the reaction product. The resulting substrate was leftstanding in an environment at 60° C. for 10 minutes, thereby completingthe oxidation polymerization, and then washed with water. Thispolymerization reaction and washing process each was repeated 10 times.The capacitor device obtained was evaluated. The results obtained areshown in Tables 11 and 12. The contents of sulfate ion and9,10-dimethoxy-anthracene-2-sulfonate ion in the polymer compositionwere determined by the method described in Example 25. As a result, thesulfate ion content was 1.8 mol % and the9,10-dimethoxy-anthracene-2-sulfonate ion content was 8.1 mol %. Thesolid electrolyte layer had an electric conductivity of 60 S/cm.

EXAMPLE 27

[0341] A dielectric material prepared by the method described in Example25 was dipped in an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene and then impregnated with an aqueoussolution prepared to have an APS concentration of 20 wt % and a sodium9,10-dimethoxy-anthracene-2-sulfonate concentration of 0.1%. Theresulting substrate was left standing in an environment at 60° C. for 10minutes, thereby completing the oxidation polymerization, and thenwashed with water. This polymerization reaction and washing process eachwas repeated 10 times. The capacitor device obtained was evaluated. Theresults obtained are shown in Tables 11 and 12. The contents of sulfateion and 9,10-dimethoxy-anthracene-2-sulfonate ion in the polymercomposition were determined by the method described in Example 25. As aresult, the sulfate ion content was 2.2 mol % and the9,10-dimethoxy-anthracene-2-sulfonate ion content was 0.6 mol %. Thesolid electrolyte layer had an electric conductivity of 65 S/cm.

EXAMPLE 28

[0342] A dielectric material prepared by the method described in Example25 was impregnated with an aqueous solution prepared to have a potassiumpersulfate concentration of 10 wt % and a sodium anthracene-1-sulfonateconcentration of 0.1% and then dipped in 1.2 mol/l of an IPA solutionhaving dissolved therein 5 g of 3,4-dioxyethylene-thiophene Theresulting substrate was left standing in an environment at 60° C. for 10minutes, thereby completing the oxidation polymerization, and thenwashed with water. This dipping process was repeated 10 times and thenthe substrate was washed with water and dried. The capacitor deviceobtained was evaluated. The results obtained are shown in Tables 11 and12. The contents of sulfate ion and anthracene-1-sulfonate ion in thepolymer composition were determined by the method described inExample 1. As a result, the sulfate ion content was 5.8 mol % and theanthracene-2-sulfonate ion content was 15 mol %. The solid electrolytelayer had an electric conductivity of 75 S/cm.

EXAMPLE 29

[0343] A dielectric material was prepared by the method described inExample 25 and the surface of the dielectric material was impregnatedwith an aqueous solution prepared to have an APS concentration of 35 wt% and then dipped in an IPA/water mixed solution prepared by addingtetrabutylammonium 9,10-dihexyl-anthracene-2-sulfonate (DHASTB) to 1.2mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene to have a DMASTB concentration of 0.04 wt %.The above-mentioned DHASTB salt used was prepared from sodium9,10-dimethoxy-anthracene-2-sulfonate (manufactured by Aldrich Co.) bythe following method. That is, sodium9,10-dimethoxy-anthracene-2-sulfonate was reacted with thionyl chloridein an anhydrous dimethylformamide solvent to prepare a sulfonyl chlorideform, which was then reacted with methanol to obtain methyl sulfonateform. Thereafter, the dimethoxy group was split with aluminum iodide tosynthesize methyl 9,10-dihydro-anthracene-2-sulfonate. Then, in thepresence of potassium carbonate, this was reacted with hexyl bromide,followed by treatment with alkali to obtain sodium9,10-dihexyloxy-anthracene-2-sulfonate. Further, this was reacted withtetrabutylammonium bromide in an aqueous solution to synthesize DHASTBsalt. For the evaluation of a capacitor device, recrystallized productwas used.

[0344] The resulting substrate was left standing in an environment at60° C. for 10 minutes, thereby completing the oxidation polymerization,and then washed with water. This dipping process was repeated 10 timesand then the substrate was washed with water and dried. Then, thecapacitor device obtained was evaluated. The results obtained are shownin Tables 11 and 12. The contents of sulfate ion and9,10-dihexyloxy-anthracene-2-sulfonate ion in the polymer compositionwere determined by the method described in Example 25. As a result, thesulfate ion content was 6.2 mol % and the9,10-dihexyloxy-anthracene-2-sulfonate ion content was 7.6 mol %. Thesolid electrolyte layer had an electric conductivity of 42 S/cm.

EXAMPLE 30

[0345] A dielectric material prepared by the method described in Example25 was dipped in an deaerated IPA solution (1.2 mol/l concentration) of5,6-dimethoxy-isothianaphthene synthesized and purified by sublimationaccording to the method described in JP-A-2-242816 and then impregnatedwith an aqueous solution prepared to have an APS concentration of 20 wt% and a sodium anthracene-1-sulfonate concentration of 0.1%. Theresulting substrate was taken out and left standing in an environment at60° C. for 10 minutes, thereby completing the oxidation polymerization.This dipping process was repeated 10 times and then the substrate waswashed with water and dried. The capacitor device obtained wasevaluated. The results obtained are shown in Tables 11 and 12. Thecontents of sulfate ion and anthracene-1-sulfonate ion in the polymercomposition were determined by the method described in Example 25. As aresult, the sulfate ion content was 0.8 mol % and theanthracene-1-sulfonate ion content was 5.6mol %. The solid electrolytelayer had an electric conductivity of 30 S/cm.

EXAMPLE 31

[0346] A capacitor device was manufactured through the same process asdescribed in Example 25 except for using the same concentration ofpyrrole-N-methyl in place of 3,4-dioxyethylene-thiophene used in Example25 and the capacitor device was evaluated. The results obtained areshown in Tables 11 and 12. The contents of sulfate ion andanthracene-2-sulfonate ion in the polymer composition were determined bythe method described in Example 25. As a result, the sulfate ion contentwas 6.9 mol % and the anthracene-2-sulfonate ion content was 15.8 mol %.The solid electrolyte layer had an electric conductivity of 5 S/cm.

EXAMPLE 32

[0347] A formed aluminum foil processed to have a prescribed area wassubjected to forming at 13 V in an aqueous 10 wt % ammonium adipatesolution to prepare a dielectric material on the aluminum foil. Thesurface of this dielectric material was impregnated with a 30 wt %DMF-IPA solution prepared to have a sodium anthracene-2-sulfonateconcentration of 0.1 wt % and a 3,4-dioxyethylene-thiopheneconcentration of 1.2 mol/l, and then the dielectric foil was dipped inan aqueous 20 wt % APS solution. The resulting substrate was taken outand left standing in an environment at 60° C. for 10 minutes, therebycompleting the oxidative polymerization, and then the substrate waswashed with water. This dipping process was repeated 10 times and thenthe substrate was washed with water and dried. The capacitor deviceobtained was evaluated. The results obtained are shown in Tables 11 and12. As a result, the sulfate ion content was 1.7 mol % and theanthracene-2-sulfonate ion content was 32 mol % based on the totalrepeating units of the polymer. The solid electrolyte layer had anelectric conductivity of 75 S/cm.

Reference Example 4

[0348] A process for manufacturing a capacitor device was performedunder the same conditions as in Example 25 except for using thiophene inplace of 3,4-dioxyethylene-thiophene used in Example 25. However, blackblue polythiophene was not produced at all and thus, polymerization ofthiophene was not caused by the action of APS. In other words,occurrence of the oxidation polymerization of a thiophene by APS waspeculiar to 3,4-dioxy-ethylene group-substituted thiophenes.

Comparative Example 14

[0349] A formed dielectric material was prepared in the same manner asin Example 25 and the dielectric material obtained was dipped in a 12%IPA solution of ferric anthracene-2-sulfonate and then dipped in 1.2mol/l of an IPA solution having dissolved therein 5 g of3,4-dioxyethylene-thiophene. The resulting substrate was left standingin an environment at 60° C. for 10 minutes, thereby completing theoxidative polymerization, and then the substrate was washed with water.This polymerization reaction and washing process each was repeated 10times. The polymer composition was reduced by hydrazine in a water/IPAsolvent and then carefully extracted and the content ofanthracene-2-sulfonate ion in the polymer composition was determined byion chromatography method. As a result, the anthraquinone-2-sulfonateion content was 16 mol % based on the total repeating units of thepolymer of the polymer composition. The solid electrolyte layer had anelectric conductivity of 32 S/cm. Thereafter, a capacitor device wasmanufactured and examined on the sparking voltage and other capacitorproperties in the same manner as in Example 25. The results obtained areshown in Tables 11 and 12.

Comparative Example 15

[0350] A capacitor device was prepared and evaluated in the same manneras in Example 25 except for changing the concentration of APS used inExample 25 from 20 wt % to 12 wt %. The results obtained are shown inTables 11 and 12. The contents of sulfate ion and anthracene-2-sulfonateion in the polymer composition were determined by the method describedin Example 25. As a result, the sulfate ion content was 0.15 mol % andthe anthracene-2-sulfonate ion content was 27 mol %. The solidelectrolyte had an electric conductivity of 36 S/cm.

Comparative Example 16

[0351] A capacitor device was prepared and evaluated in the same manneras in Example 25 except for using a solution prepared to have a ferricsulfate concentration of 10 wt % and a sodium anthracene-2-sulfonateconcentration of 0.1 wt % in place of APS used in Example 25. Theresults obtained are shown in Tables 11 and 12. The contents of sulfateion and anthracene-2-sulfonate ion in the polymer composition weredetermined by the method described in Example 25. As a result, thesulfate ion content was 23.6 mol % and the anthracenesulfonate ioncontent was 33.8 mol %. In the polymer composition, 8 wt % of iron ion(ferric and ferrous) was present and the sulfate ion content exceeded 10wt % and as a result the capacitor exhibited poor properties.

Comparative Example 17

[0352] A capacitor device was prepared and evaluated in the same manneras in Example 25 except for using thiophene in place of3,4-dioxyethylene-thiophene used in Example 25 and preparing a solutionto have a concentration of ferric chloride used in place of APS, of 10wt % and a sodium anthracene-2-sulfonate concentration of 0.1 wt %. Theresults obtained are shown in Tables 11 and 12. Theanthracene-2-sulfonate ion content in the polymer composition wasdetermined by the method described in Example 25 and found to be 2.9 mol%. Since sulfate ion was not used in combination, the capacitorexhibited poor properties. TABLE 11 Sparking Voltage (unit: V, n = 5)Number of Reaction Times 1 2 3 4 5 6 8 10 Example 25 19 19 19 19 19 1919 19 Example 26 19 19 19 19 19 19 19 19 Example 27 19 19 19 19 19 19 1919 Example 28 19 19 19 18 17 16 14 10 Example 29 19 19 19 19 19 19 19 19Example 30 19 19 19 19 19 19 19 19 Example 31 19 19 19 19 19 19 19 19Example 32 19 19 19 19 19 19 19 19 Comparative 19 16 12 6 3 Example 14Comparative 19 19 19 19 19 19 19 19 Example 15 Comparative 19 17 13 5Example 16 Comparative 18 15 11 3 Example 17

[0353] TABLE 12 Initial Characteristics Number Ratio of of C DF Z LCDefective/Sample Short (μF) (%) (mΩ) (μA) (units/units) Circuit Example25 8.2 0.7 60 0.02 0/30 0 Example 26 8.0 0.7 60 0.02 0/30 0 Example 277.5 0.8 60 0.03 0/30 0 Example 28 7.1 0.7 60 0.04 1/30 0 Example 29 6.80.9 60 0.05 1/30 0 Example 30 6.7 0.8 60 0.05 1/30 0 Example 31 4.1 1.260 0.10 1/30 0 Example 32 8.1 0.7 60 0.02 1/30 0 Comparative 6.9 1.3 600.16 9/30 7 Example 14 Comparative 6.8 0.6 60 0.09 1/30 0 Example 15Comparative 6.0 3.2 85 0.41 14/30  9 Example 16 Comparative 5.8 3.3 910.42 28/30  17  Example 17

[0354] As will be apparent from Table 11, in the sparking voltage testof Examples 25 to 32, substantially no decrease in voltage was observedat the initial stage, the sparking voltage at the completion of thereaction was 19 V or less in each Example. In Comparative Example 16using ferric sulfate, the sparking voltage was largely reduced due toremaining of iron ion (ferric and ferrous ions) in a concentration ashigh as 8 wt % and the sparking voltage could not withstand until theprescribed reaction was completed. As a result, the solid electrolytewas insufficiently filled and this was disadvantageous.

Industrial Applicability

[0355] The solid electrolytic capacitor device of the present invention,firstly, has a lamellar structure in the solid electrolyte layer andfurther advantageously has void spaces between the layers so that it isexcellent in thermal relaxation ability, adhesion to electricallyconducting paste layer, and ability of recovering dielectric film.

[0356] Secondly, since a specified condensed heterocyclic polymer isused as the solid electrolyte, the capacitor of the present invention isexcellent in soldering heat resistance (reflow property) and thermalstability and also has good humidity resistance property. It has a highcapacitance and low impedance. Also, its leakage current is low.

[0357] Thirdly, use of the above-mentioned polymer to form a lamellarstructure and preferably further provision of a space portion thereingives rise to a solid electrolytic capacitor having excellent ability ofrelaxing thermal stress and excellent soldering heat resistance.

[0358] In particular, a solid electrolytic capacitor containing asulfoquinone having at least one sulfoanion group and a quinonestructure in the molecule in the solid electrolyte and an other anionother than the sulfoquinone, having a dopant function in combination,with the content of the sulfoquinone being 0.1-50 wt % and the sulfateion content being 0.1-10 wt % and a solid electrolytic capacitorcontaining at least one anthracenemonosulfonic acid selected fromanthracenesulfonic acid or derivatives thereof having a sulfonic acidgroup as a dopant in the solid electrolyte electrolyte and an otheranion other than the sulfoquinone, having a dopant function incombination, with the content of the anthracenemonosulfonate being0.1-50 wt % and the sulfate ion content being 0.1-10 wt % have greatlyimproved voltage resistant property (a sparking voltage test), highfrequency property, tan δ, impedance property, leakage current, heatresistance (reflow property), etc., and has low impedance, is small insize and exhibits a high performance.

1. A solid electrolytic capacitor comprising a valve acting metal havingpores, a dielectric film formed on a surface of the valve acting metal,and a solid electrolyte layer provided on the dielectric film, whereinat least a portion of the solid electrolyte layer is of a lamellarstructure.
 2. The solid electrolytic capacitor described in claim 1, inwhich the solid electrolyte layer is formed on an outer surface of thedielectric film or on the outer surface and inside the pores.
 3. Thesolid electrolytic capacitor as claimed in claim 1 or 2, in which atleast a portion of interlayer portion in the lamellar structurecomprises a space portion.
 4. The solid electrolytic capacitor asclaimed in any one of claims 1 to 3, in which each unit layer of thesolid electrolyte constituting the lamellar structure has a thickness inthe range of 0.01-5 μm and a total thickness of the solid electrolytelayer is in the range of 1-200 μm.
 5. The solid electrolytic capacitoras claimed in any one of claims 1 to 4, in which the solid electrolytelayer comprises a composition containing a π-electron conjugate polymerand/or other electrically conducting polymer.
 6. The solid electrolyticcapacitor as claimed in claim 5, in which the electrically conductingpolymer comprises as a repeating unit a structural unit represented bygeneral formula (I) below

(wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6(meaning 1 to 6 carbon atoms, hereafter the same) alkyl group, a linearor branched, saturated or unsaturated C1-6 alkoxy group, a hydroxylgroup, a halogen atom, a nitro group, a cyano group, a trihalomethylgroup, a phenyl group and a substituted phenyl group, R¹ and R² may becombined to each other at any position to form at least one divalentchain for forming at least one 5-, 6- or 7-membered saturated orunsaturated ring structure, X represents a hetero atom selected from S,O, Se, Te or NR³, R³represents a hydrogen atom, a linear or branched,saturated or unsaturated C1-6 alkyl group, a phenyl group or a linear orbranched, saturated or unsaturated C1-6 alkoxy, the alkyl group and thealkoxy group represented by R¹, R²or R³may optionally contain in thechain thereof a carbonyl bond, an ether bond, an ester bond, an amidebond or an imino bond, and δ represents a number of from 0 to 1).
 7. Thesolid electrolytic capacitor as claimed in claim 5, in which theelectrically conducting polymer comprises as a repeating unit astructural unit represented by general formula (II) below

(wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedcyclic structure containing the two oxygen elements shown in the formulaby combining the C1-6 alkyl groups to each other at any position, thering structure formed in the scope thereof includes a chemical structuresuch as a vinylene group which may be substituted and a phenylene groupwhich may be substituted, and δ represents a number of from 0 to 1). 8.The solid electrolytic capacitor as claimed in claim 5, in which theelectrically conducting polymer is a condensed heteropolycyclic polymercomprising as a repeating unit a structural unit represented by generalformula (III) below

(wherein the substituents R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ each independentlyrepresents a monovalent group selected from the group consisting of ahydrogen atom, a linear or branched, saturated or unsaturated C1-10alkyl, alkoxy or alkyl ester group, a halogen atom, a nitro group, acyano group, a primary, secondary or tertiary amino group, atrihalomethyl group, a phenyl group and a substituted phenyl group, thealkyl chains of R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ may combine to each other atany position to form at least one divalent chain for forming at leastone 3-, 4-, 5-, 6- or 7-membered saturated or unsaturated hydrocarboncyclic structure together with the carbon atoms to which thesubstituents are bonded, the alkyl group, the alkoxy group or the alkylester group of R⁶, R⁷, R⁸, R⁹, R²⁰ or R¹¹ or the cyclic hydrocarbonchain formed by the substituents may contain any number of any ofcarbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and iminobonds, k represents a number of the condensed ring enclosed by thethiophene ring and the benzene ring having substituents R⁶ to R⁹ andrepresents an integer of from 0 to 3 excluding a form in which all of R⁶to R⁹ represent a hydrogen atom from among derivatives in which K=0, andthe condensed ring may optionally contain 1 to 2 nitrogen atoms (N) orN-oxide, δ is in the range of 0 to 1, Z represents an anion, j is avalency of Z and is 1 or 2.)
 9. The solid electrolytic capacitor asclaimed in claim 8, in which the condensed heteropolycyclic polymerrepresented by general formula (III) is a condensed heteropolycyclicpolymer comprising represented by general formula (IV) below where K=0

(wherein R⁶, R⁷, R⁸, R⁹, δ, Z and j are the same as in formula (III),and the condensed ring may optionally contain 1 to 2 nitrogen atoms (N)or N-oxide).
 10. The solid electrolytic capacitor as claimed in claim 9,in which the condensed heteropolycyclic polymer represented by generalformula (IV) above is a condensed heteropolycyclic polymer selected from5,6-dioxymethylene-isothianaphthenylene polymer and and5,6-dimethoxy-isothianaphthenylene polymer.
 11. The solid electrolyticcapacitor as claimed in claim 8, in which the condensed heteropolycyclicpolymer represented by general formula (III) is a condensedheteropolycyclic polymer comprising represented by general formula (V)below where k=1

(wherein R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, δ, Z and j are the same as in formula(III), and the condensed ring may optionally contain 1 to 2 nitrogenatoms (N) or N-oxide).
 12. The solid electrolytic capacitor as claimedin claim 5, in which the electrically conducting polymer is anelectrically conducting polythiophene and the composition containing theelectrically conducting polythiophene contains a sulfate ion in therange of 0.1-10 mol % and a naphthalenesulfonate ion in the range of1-50 mol %.
 13. The solid electrolytic capacitor as claimed in claim 12,in which the electrically conducting polythiophene contains as arepeating unit the structural unit represented by general formula (II)described in (7) above.
 14. The solid electrolytic capacitor as claimedin claims 12 or 13, in which the sulfate ion is derived from a reducedform of persulfate.
 15. A solid electrolytic capacitor comprising avalve acting metal having pores, a dielectric film formed on a surfaceof the valve acting metal, and a solid electrolyte layer comprising anelectrically conducting polymer composition layer provided on thedielectric film, in which the composition contains sulfoquinone anionhaving at least one sulfo anion group and a quinone structure in themolecule in an amount of 0.1-50 mol % and an anion other than thesulfoquinone anion in the range of 0.1-10 mol %.
 16. The solidelectrolytic capacitor as claimed in claim 15, in which a main chain ofthe electrically conducting polymer in the composition contains astructural unit represented by general formula (I) below

(wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6alkyl, a linear or branched, saturated or unsaturated C1-6 alkoxy group,a hydroxyl group, a halogen atom, a nitro group, a cyano group, atrihalomethyl group, a phenyl group and a substituted phenyl group, R¹and R² may be combined to each other at any position to form at leastone divalent chain for forming at least one 5-, 6- or 7-memberedsaturated or unsaturated ring structure, X represents a hetero atomselected from S, O, Se, Te or NR³, R³represents H, a linear or branched,saturated or unsaturated C1-6 hydrocarbon group, a phenyl group or alinear or branched, saturated or unsaturated C1-6 alkoxy group, thealkyl group and the alkoxy group represented by R¹, R² or R³mayoptionally contain in the chain thereof a carbonyl bond, an ether bond,an ester bond, an amide bond or an imino bond, and δ represents a numberof from 0 to 1).
 17. The solid electrolytic capacitor as claimed inclaim 16, in which the structural unit represented by formula (I) is achemical structure represented by the following formula (II):

(wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedheterocyclic structure containing the two oxygen elements shown in theformula by combining the C1-6 alkyl groups to each other at anyposition, the ring structure formed in the scope thereof includes achemical structure such as a vinylene group which may be substituted anda substituted phenylene group which may be substituted, and δ representsa number of from 0 to 1).
 18. The solid electrolytic capacitor asclaimed in any one of claims 15 to 17, in which a base structure of thesulfoquinone anion is at least one selected from the group consisting ofp-benzoquinone, o-benzoquinone, 1,2-naphthoquinone, 1,4-naphthoquinone,2,6-naphthoquinone, 9,10-anthraquinone, 1,4-anthraquinone,1,2-anthraquinone, 1,4-chrysenequinone, 5,6-chrysenequinone,6,12-chrysenequinone, acenaphthoquinone, acenaphthenequinone,camphorquinone, 2,3-bornadione, 9,10-phenanthrenequinone, and2,7-pyrenequinone.
 19. The solid electrolytic capacitor as claimed inclaim 18, in which the sulfoquinone contains in the molecule thereof asulfoquinone having at least one sulfoanion group and a quinonestructure and a hydroquinone structure and/or quinhydrone structurethereof produced from the sulfoquinone.
 20. The solid electrolyticcapacitor as claimed in any of claims 15 to 19, in which the anion otherthan the sulfoquinone anion is a reduced form anion of an oxidizingagent.
 21. The solid electrolytic capacitor as claimed in claim 20, inwhich the reduced form anion of an oxidizing agent is a sulfate ion. 22.A solid electrolytic capacitor comprising a valve acting metal havingpores, a dielectric film formed on a surface of the valve acting metal,and a solid electrolyte layer comprising an electrically conductingpolymer composition layer provided on the dielectric film, in which thecomposition contains at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having a sulfonate group or derivativesthereof as a dopant.
 23. The solid electrolytic capacitor as claimed inclaim 20, in which the solid electrolytic capacitor as claimed in claim22, in which the anthracenemonosulfonate anion is contained in the rangeof 0.1-50 mol % of total repeating unit of the electrically conductingpolymer.
 24. The solid electrolytic capacitor as claimed in claim 22 or23, which contains in addition to the anthracene monosulfonate anion areduced form anion of an oxidizing agent in the range of 0.1-10 mol %.25. The solid electrolytic capacitor as claimed in claim 24, in whichthe reduced form anion of an oxidizing agent is a sulfate ion.
 26. Thesolid electrolytic capacitor as claimed in any one of claims 22 to 25,in which the anthracenesulfonic acid derivative isanthracenemonosulfonic acid of which at least one of hydrogen a toms onan anthracene ring is substituted by a C1-12 linear or branched,saturated or unsaturated hydrocarbon group or alkoxy group.
 27. Thesolid electrolytic capacitor as claimed in claim 22, in which a mainchain of the electrically conducting polymer in the composition containsa structural unit represented by general formula (I) below

(wherein the substituents R¹ and R² each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6alkyl, a linear or branched, saturated or unsaturated C1-6 alkoxy group,a hydroxyl group, a halogen atom, a nitro group, a cyano group, atrihalomethyl group, a phenyl group and a substituted phenyl group, R¹and R² may be combined to each other at any position to form at leastone divalent chain for forming at least one 5-, 6- or 7-memberedsaturated or unsaturated ring structure, X represents a hetero atomselected from S, O, Se, Te or NR³, R³ represents H, a linear orbranched, saturated or unsaturated C1-6 hydrocarbon group, a phenylgroup or an alkoxy group having a linear or branched, saturated orunsaturated C1-6 alkoxy group, the alkyl group and the alkoxy grouprepresented by R¹, R² or R³ may optionally contain in the chain thereofa carbonyl bond, an ether bond, an ester bond, an amide bond or an iminobond, and δ represents a number of from 0 to 1).
 28. The solidelectrolytic capacitor as claimed in claim 27, in which the structuralunit represented by formula (I) is a chemical structure represented bythe following formula (II):

(wherein the substituents R⁴ and R⁵ each independently representshydrogen atom, a linear or branched, saturated or unsaturated C1-6 alkylgroup or a substituent for forming at least one 5-, 6- or 7-memberedcyclic structure containing the two oxygen elements shown in the formulaby combining the C1-6 alkyl groups to each other at any position, thering structure formed in the scope thereof includes a chemical structuresuch as a vinylene group which may be substituted and a substitutedphenylene group which may be substituted, and δ represents a number offrom 0 to 1).
 29. A method for producing a solid electrolytic capacitoras claimed in claim 1 comprising a valve acting metal having pores, adielectric film formed on a surface of the valve acting metal, and asolid electrolyte layer provided on the dielectric film, the methodcomprising polymerizing a condensed heteropolycyclic compoundrepresented by the following formula (VI):

(wherein the substituents R⁶, R⁷, R⁸, R⁹, R¹⁰ and R¹¹ each independentlyrepresents a monovalent group selected from the group consisting of H, alinear or branched, saturated or unsaturated C1-10 alkyl, alkoxy oralkylester group, a halogen, a nitro group, a cyano group, a primary,secondary or tertiary amino group, a trihalomethyl group, a phenyl groupand a substituted phenyl group, the alkyl chains of R⁶, R⁷, R⁸, R⁹, R¹⁰and R¹¹ may combine to each other at any position to form at least onedivalent chain for forming at least one 3-, 4-, 5-, 6- or 7-memberedsaturated or unsaturated hydrocarbon cyclic structure together with thecarbon atoms to which the substituents are bonded, the alkyl group, thealkoxy group or the alkylester group of R⁶, R⁷, R⁸, R⁹, R¹⁰ or R¹¹ orthe cyclic hydrocarbon chain formed by the substituents may contain anyof carbonyl, ether, ester, amide, sulfide, sulfinyl, sulfonyl and iminobonds, k represents a number of the condensed ring enclosed by thethiophene ring and the benzene ring having substituents R⁶ to R⁹ andrepresents an integer of from 0 to 3, and the condensed ring mayoptionally contain nitrogen or N-oxide) alone or together with anotheranion having a dopant ability, on the dielectric film formed on a porousvalve acting metal surface by the action of an oxidizing agent to form asolid electrolyte layer on the dielectric film.
 30. The method forproducing a solid electrolytic capacitor, as claimed in claim 29, inwhich as the condensed heteropolycyclic compound, there is used at leastone member selected from dihydroisothianaphthene,dihydronaphtho[2,3-c]thiophene and dihydrothieno[3,4-b]quinoxalinederivatives.
 31. The method for producing a solid electrolyticcapacitor, as claimed in claim 29, in which at least one member selectedfrom 1,3-dihydroisothianaphthene,5,6-dioxymethylene-1,3-dihydroisothianaphthene,5,6-dimethoxy-1,3-dihydroisothianaphthene,1,3-dihydronaphtho[2,3-c]thiophene and1,3-dihydrothieno[3,4-b]quinoxaline.
 32. A method for producing a solidelectrolytic capacitor as claimed in claim 1 comprising a valve actingmetal having pores, a dielectric film formed on a surface of the valveacting metal, and a solid electrolyte layer provided on the dielectricfilm, the method comprising polymerizing a condensed heteropolycycliccompound represented by the following formula (VII):

(wherein the substituents R⁶ ₁ R⁷, R⁸, R⁹, R¹⁰ and R¹¹ and k have thesame meanings as in general formula (VI) described in (29) above, andthe condensed ring may optionally contain 1 to 2 nitrogen atoms (N) orN-oxide) alone or together with another anion having a dopant ability,on the dielectric film formed on a porous valve acting metal surface bythe action of an oxidizing agent to form a solid electrolyte layer onthe dielectric film.
 33. The method for producing a solid electrolyte asclaimed in claim 32, in which as the condensed heteropolycycliccompound, there is used at least one member selected fromdihydroisothianaphthene-2-oxide, dihydronaphtho[2,3-c]thiophene-2-oxideand dihydrothieno[3,4-b]quinoxaline-2-oxide derivatives.
 34. The methodfor producing a solid electrolytic capacitor, as claimed in claim 32 inwhich at least one member selected from1,3-dihydroisothianaphthene-2-oxide,5,6-dioxymethylene-1,3-dihydroisothianaphthene-2-oxide,5,6-dimethoxy-1,3-dihydroisothianaphthene-2-oxide,1,3-dihydronaphtho[2,3-c]thiophene-2-oxide and1,3-dihydrothieno[3,4-b]quinoxaline-2-oxide.
 35. A method for producinga solid electrolytic capacitor as claimed in claim 1 comprising a valveacting metal having pores, a dielectric film formed on a surface of thevalve acting metal, and an electrically conducting polythiophenecomposition as a solid electrolyte provided on the dielectric film, themethod comprising polymerizing a thiophene monomer represented by thefollowing formula (IX):

(wherein R⁴ and R⁵ have the same meanings as defined in (17) above) inthe presence of naphthalenesulfonate anion by the action of a persulfateto form a solid electrolyte layer on the dielectric film.
 36. The methodfor producing a capacitor as claimed in claim 35, in which thepersulfate is ammonium persulfate or potassium persulfate.
 37. Themethod for producing a capacitor as claimed in any one of claims 29 to36, in which the polymerization by the action of an oxidizing agentwithin the metal oxide pores in the dielectric layer is repeated atleast twice.
 38. A method for producing a capacitor as claimed in claim15 comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an electrically conducting polymer composition layerprovided on the dielectric film, in which the method comprisespolymerizing a monomer compound represented by the following formula(VIII):

(wherein R¹, R² and X have the same meanings as defined in claim 16) inthe presence of a compound which donates a sulfoquinone anion by theaction of an oxidizing agent to form a solid electrolyte layer.
 39. Themethod for producing a solid electrolytic capacitor as claimed in claim38, in which the monomer compound represented by general formula (VIII)above is a compound represented by the following general formula (IX):

(wherein R⁴ and R² have the same meanings as defined in claim 17).
 40. Amethod for producing a solid electrolytic capacitor as claimed in claim15 comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an electrically conducting polymer composition providedon the dielectric film, the method comprising polymerizing a monomer bythe action of an oxidizing agent to form a solid electrolyte layer onthe dielectric film, in which the method comprises the steps of dippingthe valve acting metal having formed thereon the dielectric film layerin a solution containing a monomer compound, and dipping in a solutioncontaining an oxidizing agent and a sulfoquinone anion.
 41. The methodfor producing a solid electrolytic capacitor as claimed in claim 40, inwhich the valve acting metal having formed thereon the dielectric filmlayer is dipped in a solution containing a monomer compound and then ina solution containing an oxidizing agent and a sulfoquinone anion. 42.The method for producing a solid electrolytic capacitor as claimed inclaim 43, in which the method comprises the step of repeating in aplurality of times the steps of dipping the valve acting metal havingformed thereon the dielectric film layer in a solution containing amonomer compound and then dipping the metal in a solution containing anoxidizing agent and a sulfoquinone anion.
 43. The method for producing asolid electrolytic capacitor as claimed in claim 42, in which the methodcomprises the step of repeating in a plurality of times the steps ofdipping the valve acting metal having formed thereon the dielectric filmlayer in a solution containing a monomer compound and then dipping themetal in a solution containing an oxidizing agent and a sulfoquinoneanion, followed by washing and drying.
 44. The method for producing asolid electrolytic capacitor as claimed in claim 40, in which the methodcomprises the step of dipping the valve acting metal having formedthereon the dielectric film in a solution containing an oxidizing agentand a sulfoquinone anion and then dipping the metal in a solutioncontaining a monomer compound.
 45. The method for producing a solidelectrolytic capacitor as claimed in claim 44, in which the methodcomprises the step of repeating in a plurality of times the steps ofdipping the valve acting metal having formed thereon the dielectric filmin a solution containing an oxidizing agent and a sulfoquinone anion andthen dipping the metal in a solution containing a monomer compound. 46.The method for producing a solid electrolytic capacitor as claimed inclaim 45, in which the method comprises the step of repeating in aplurality of times the steps of dipping the valve acting metal havingformed thereon the dielectric film in a solution containing an oxidizingagent and a sulfoquinone anion and then dipping the metal in a solutioncontaining a monomer compound, followed by washing and drying.
 47. Amethod for producing a solid electrolytic capacitor as claimed in claim15 comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an electrically conducting polymer composition providedon the dielectric film, the method comprising polymerizing a monomer bythe action of an oxidizing agent to form a solid electrolyte layer onthe dielectric film, in which the method comprises the steps of dippingthe valve acting metal having formed thereon the dielectric film layerin a solution containing an oxidizing agent and of dipping the metal ina solution containing a monomer compound and a sulfoquinone anion. 48.The method for producing a solid electrolytic capacitor as claimed inclaim 47, in which the valve acting metal having formed thereon thedielectric film layer is dipped in a solution containing an oxidizingagent and then in a solution containing a monomer compound and asulfoquinone anion.
 49. The method for producing a solid electrolyticcapacitor as claimed in claim 48, in which the method comprises the stepof repeating in a plurality of times the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing an oxidizing agent and then dipping the metal in asolution containing a monomer compound and a sulfoquinone anion.
 50. Themethod for producing a solid electrolytic capacitor as claimed in claim49, in which the method comprises the step of repeating in a pluralityof times the steps of dipping the valve acting metal having formedthereon the dielectric film layer in a solution containing an oxidizingagent and then dipping the metal in a solution containing a monomercompound and a sulfoquinone anion, followed by washing and drying. 51.The method for producing a solid electrolytic capacitor as claimed inclaim 47, in which the valve acting metal having formed thereon thedielectric film layer is dipped in a solution containing a monomercompound and a sulfoquinone anion and then in a solution containing anoxidizing agent.
 52. The method for producing a solid electrolyticcapacitor as claimed in claim 51, in which the method comprises the stepof repeating in a plurality of times the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing a monomer compound and a sulfoquinone anion and thendipping the metal in a solution containing an oxidizing agent.
 53. Themethod for producing a solid electrolytic capacitor as claimed in claim52, in which the method comprises the step of repeating in a pluralityof times the steps of dipping the valve acting metal having formedthereon the dielectric film layer in a solution containing a monomercompound and a sulfoquinone anion and then dipping the metal in asolution containing an oxidizing agent, followed by washing and drying.54. The method for producing a solid electrolytic capacitor as claimedin any one of claims 38 to 53, in which the oxidizing agent is apersulfate.
 55. The method for producing a solid electrolytic capacitoras claimed in any one of claims 40 to 53, in which the oxidizing agentis a persulfate and the monomer compound is a compound represented bythe following general formula (VIII)

(wherein R¹, R²and X have the same meanings as defined in claim 16). 56.The method for producing a solid electrolytic capacitor as claimed inclaim 55, in which the monomer compound represented by the generalformula (VIII) above is a compound represented by the following generalformula (IX)

(wherein R⁴ and R⁵ have the same meanings as defined in claim 17).
 57. Amethod for producing a capacitor as claimed in claim 22 comprising avalve acting metal having pores, a dielectric film formed on a surfaceof the valve acting metal, and a solid electrolyte layer comprising anelectrically conducting polymer composition layer provided on thedielectric film, the method comprising polymerizing a monomer compoundby the action of an oxidizing agent on the oxide dielectric film, inwhich the compound represented by the following formula (VIII):

(wherein R¹, R² and X have the same meanings as defined in claim 27) ispolymerized in the presence of a compound which donates at least oneanthracenemonosulfonate anion selected from anthracenesulfonic acid andderivatives thereof to form a solid electrolyte layer.
 59. The methodfor producing a solid electrolytic capacitor as claimed in claim 57, inwhich the monomer compound represented by general formula (VIII) aboveis a compound represented by the following general formula (IX):

(wherein R⁴ and R⁵ have the same meanings as defined in claim 28).
 59. Amethod for producing a solid electrolytic capacitor as claimed in claim22 comprising a valve acting metal having pores, a dielectric filmformed on a surface of the valve acting metal, and a solid electrolytelayer comprising an electrically conducting polymer composition providedon the dielectric film, the method comprising polymerizing a monomer bythe action of an oxidizing agent to form a solid electrolyte layer onthe dielectric film, in which the method comprises the steps of dippingthe valve acting metal having formed thereon the dielectric film layerin a solution containing a monomer compound, and dipping in a solutioncontaining an oxidizing agent and at least one anthracenemonosulfonateanion selected from anthracenesulfonic acid having one sulfonate groupand derivatives thereof.
 60. The method for producing a solidelectrolytic capacitor as claimed in claim 59, in which the valve actingmetal having formed thereon the dielectric film layer is dipped in asolution containing a monomer compound and then in a solution containingan oxidizing agent and at least one anthracenemonosulfonate anionselected from anthracenesulfonic acid having a sulfonate group andderivatives thereof.
 61. The method for producing a solid electrolyticcapacitor as claimed in claim 60, in which the method comprises the stepof repeating in a plurality of times the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing a monomer compound and then dipping the metal in asolution containing an oxidizing agent and at least oneanthracenemonosulfonate anion selected from anthracenesulfonic acidhaving one sulfonate group and derivatives thereof.
 62. The method forproducing a solid electrolytic capacitor as claimed in claim 61, inwhich the method comprises the step of repeating in a plurality of timesthe steps of dipping the valve acting metal having formed thereon thedielectric film layer in a solution containing a monomer compound andthen dipping the metal in a solution containing an oxidizing agent andat least one anthracenemonosulfonate anion selected fromanthracenesulfonic acid having one sulfonate group and derivativesthereof, followed by washing and drying.
 63. The method for producing asolid electrolytic capacitor as claimed in claim 59, in which the methodcomprises the step of dipping the valve acting metal having formedthereon the dielectric film in a solution containing an oxidizing agentand at least one anthracenemonosulfonate anion selected fromanthracenesulfonic acid having one sulfonate group and derivativesthereof and then dipping the metal in a solution containing a monomercompound.
 64. The method for producing a solid electrolytic capacitor asclaimed in claim 63, in which the method comprises the step of repeatingin a plurality of times the steps of dipping the valve acting metalhaving formed thereon the dielectric film in a solution containing anoxidizing agent and at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having one sulfonate group and derivativesthereof and then dipping the metal in a solution containing a monomercompound.
 65. The method for producing a solid electrolytic capacitor asclaimed in claim 64, in which the method comprises the step of repeatingin a plurality of times the steps of dipping the valve acting metalhaving formed thereon the dielectric film in a solution containing anoxidizing agent and at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having one sulfonate group and derivativesthereof and then dipping the metal in a solution containing a monomercompound, followed by washing and drying.
 66. A method for producing asolid electrolytic capacitor as claimed in claim 22 comprising a valveacting metal having pores, a dielectric film formed on a surface of thevalve acting metal, and a solid electrolyte layer comprising anelectrically conducting polymer composition provided on the dielectricfilm, the method comprising polymerizing a monomer by the action of anoxidizing agent to form a solid electrolyte layer on the dielectricfilm, in which the method comprises the steps of dipping the valveacting metal having formed thereon the dielectric film layer in asolution containing an oxidizing agent and of dipping the metal in asolution containing a monomer compound and an anthracenemonosulfonateanion.
 67. The method for producing a solid electrolytic capacitor asclaimed in claim 66, in which the valve acting metal having formedthereon the dielectric film layer is dipped in a solution containing anoxidizing agent and then in a solution containing a monomer compound andat least one anthracenemonosulfonate anion selected fromanthracenesulfonic acid having one sulfonate group and derivativesthereof.
 68. The method for producing a solid electrolytic capacitor asclaimed in claim 67, in which the method comprises the step of repeatingin a plurality of times the steps of dipping the valve acting metalhaving formed thereon the dielectric film layer in a solution containingan oxidizing agent and then dipping the metal in a solution containing amonomer compound and at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having one sulfonate group and derivativesthereof.
 69. The method for producing a solid electrolytic capacitor asclaimed in claim 68, in which the method comprises the step of repeatingin a plurality of times the steps of dipping the valve acting metalhaving formed thereon the dielectric film layer in a solution containingan oxidizing agent and then dipping the metal in a solution containing amonomer compound and at least one anthracenemonosulfonate anion selectedfrom anthracenesulfonic acid having one sulfonate group and derivativesthereof, followed by washing and drying.
 70. The method for producing asolid electrolytic capacitor as claimed in claim 66, in which the valveacting metal having formed thereon the dielectric film layer is dippedin a solution containing a monomer compound and at least oneanthracenemonosulfonate anion selected from anthracenesulfonic acidhaving one sulfonate group and derivatives thereof and then in asolution containing an oxidizing agent.
 71. The method for producing asolid electrolytic capacitor as claimed in claim 70, in which, themethod comprises the step of repeating in a plurality of times the stepsof dipping the valve acting metal having formed thereon the dielectricfilm layer in a solution containing a monomer compound and at least oneanthracenemonosulfonate anion selected from anthracenesulfonic acidhaving one sulfonate group and derivatives thereof and then dipping themetal in a solution containing an oxidizing agent.
 72. The method forproducing a solid electrolytic capacitor as claimed in claim 71, inwhich the method comprises the step of repeating in a plurality of timesthe steps of dipping the valve acting metal having formed thereon thedielectric film layer in a solution containing a monomer compound and atleast one anthracenemonosulfonate anion selected from anthracenesulfonicacid having one sulfonate group and derivatives thereof and then dippingthe metal in a solution containing an oxidizing agent, followed bywashing and drying.
 73. The method for producing a solid electrolyticcapacitor as claimed in any one of claims 59 to 72, in which the monomercompound is a compound represented by the following general formula(VIII)

(wherein R¹, R² and X have the same meanings as defined in claim 27).74. The method for producing a solid electrolytic capacitor as claimedin claim 73, in which the monomer compound represented by the followinggeneral formula (VIII) is a compound represented by the followinggeneral formula (IX)

(wherein R⁴ and R⁵ have the same meanings as defined in claim 28). 75.The method for producing a solid electrolytic capacitor as claimed inany one of claims 57 to 73, in which the oxidizing agent is apersulfate.